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import torch
import torch.nn.functional as F
import torch.nn as nn
import modules.components.upr_net_multi_flow.correlation as correlation
from modules.components.upr_net_multi_flow.softsplat import *
from modules.components.upr_net_multi_flow.backwarp import backwarp
from modules.components.upr_net_multi_flow.m2m import *
from ..components import register
def photometric_consistency(img0, img1, flow01):
return (img0 - backwarp(img1, flow01)).abs().sum(dim=1, keepdims=True)
def flow_consistency(flow01, flow10):
return (flow01 + backwarp(flow10, flow01)).abs().sum(dim=1, keepdims=True)
gaussian_kernel = torch.tensor([[1, 2, 1],
[2, 4, 2],
[1, 2, 1]]) / 16
gaussian_kernel = gaussian_kernel.repeat(2, 1, 1, 1)
gaussian_kernel = gaussian_kernel.to("cpu")#torch.cuda.current_device())
def gaussian(x):
x = torch.nn.functional.pad(x, (1, 1, 1, 1), mode='reflect')
out = torch.nn.functional.conv2d(x, gaussian_kernel, groups=x.shape[1])
# out = TF.gaussian_blur(x, [3, 3], sigma=[2, 2])
return out
def variance_flow(flow):
flow = flow * torch.tensor(data=[2.0 / (flow.shape[3] - 1.0), 2.0 / (flow.shape[2] - 1.0)], dtype=flow.dtype,
device=flow.device).view(1, 2, 1, 1)
return (gaussian(flow ** 2) - gaussian(flow) ** 2 + 1e-4).sqrt().abs().sum(dim=1, keepdim=True)
# **************************************************************************************************#
# => Feature Pyramid
# **************************************************************************************************#
class FeatPyramid(nn.Module):
"""A 3-level feature pyramid, which by default is shared by the motion
estimator and synthesis network.
"""
def __init__(self):
super(FeatPyramid, self).__init__()
self.conv_stage0 = nn.Sequential(
nn.Conv2d(in_channels=3, out_channels=32, kernel_size=3,
stride=1, padding=1),
nn.LeakyReLU(inplace=False, negative_slope=0.1),
nn.Conv2d(in_channels=32, out_channels=32, kernel_size=3,
stride=1, padding=1),
nn.LeakyReLU(inplace=False, negative_slope=0.1),
nn.Conv2d(in_channels=32, out_channels=32, kernel_size=3,
stride=1, padding=1),
nn.LeakyReLU(inplace=False, negative_slope=0.1),
nn.Conv2d(in_channels=32, out_channels=32, kernel_size=3,
stride=1, padding=1),
nn.LeakyReLU(inplace=False, negative_slope=0.1))
self.conv_stage1 = nn.Sequential(
nn.Conv2d(in_channels=32, out_channels=64, kernel_size=3,
stride=2, padding=1),
nn.LeakyReLU(inplace=False, negative_slope=0.1),
nn.Conv2d(in_channels=64, out_channels=64, kernel_size=3,
stride=1, padding=1),
nn.LeakyReLU(inplace=False, negative_slope=0.1),
nn.Conv2d(in_channels=64, out_channels=64, kernel_size=3,
stride=1, padding=1),
nn.LeakyReLU(inplace=False, negative_slope=0.1),
nn.Conv2d(in_channels=64, out_channels=64, kernel_size=3,
stride=1, padding=1),
nn.LeakyReLU(inplace=False, negative_slope=0.1))
self.conv_stage2 = nn.Sequential(
nn.Conv2d(in_channels=64, out_channels=128, kernel_size=3,
stride=2, padding=1),
nn.LeakyReLU(inplace=False, negative_slope=0.1),
nn.Conv2d(in_channels=128, out_channels=128, kernel_size=3,
stride=1, padding=1),
nn.LeakyReLU(inplace=False, negative_slope=0.1),
nn.Conv2d(in_channels=128, out_channels=128, kernel_size=3,
stride=1, padding=1),
nn.LeakyReLU(inplace=False, negative_slope=0.1),
nn.Conv2d(in_channels=128, out_channels=128, kernel_size=3,
stride=1, padding=1),
nn.LeakyReLU(inplace=False, negative_slope=0.1))
def forward(self, img):
C0 = self.conv_stage0(img)
C1 = self.conv_stage1(C0)
C2 = self.conv_stage2(C1)
return [C0, C1, C2]
# **************************************************************************************************#
# => Motion Estimation
# **************************************************************************************************#
class MotionEstimator(nn.Module):
"""Bi-directional optical flow estimator
1) construct partial cost volume with the CNN features from the stage 2 of
the feature pyramid;
2) estimate bi-directional flows, by feeding cost volume, CNN features for
both warped images, CNN feature and estimated flow from previous iteration.
"""
def __init__(self):
super(MotionEstimator, self).__init__()
# (4*2 + 1) ** 2 + 128 * 2 + 128 + 4 = 469
self.conv_layer1 = nn.Sequential(
nn.Conv2d(in_channels=469, out_channels=320,
kernel_size=1, stride=1, padding=0),
nn.LeakyReLU(inplace=False, negative_slope=0.1))
self.conv_layer2 = nn.Sequential(
nn.Conv2d(in_channels=320, out_channels=256,
kernel_size=3, stride=1, padding=1),
nn.LeakyReLU(inplace=False, negative_slope=0.1))
self.conv_layer3 = nn.Sequential(
nn.Conv2d(in_channels=256, out_channels=224,
kernel_size=3, stride=1, padding=1),
nn.LeakyReLU(inplace=False, negative_slope=0.1))
self.conv_layer4 = nn.Sequential(
nn.Conv2d(in_channels=224, out_channels=192,
kernel_size=3, stride=1, padding=1),
nn.LeakyReLU(inplace=False, negative_slope=0.1))
self.conv_layer5 = nn.Sequential(
nn.Conv2d(in_channels=192, out_channels=128,
kernel_size=3, stride=1, padding=1),
nn.LeakyReLU(inplace=False, negative_slope=0.1))
self.conv_layer6 = nn.Sequential(
nn.Conv2d(in_channels=128, out_channels=4,
kernel_size=3, stride=1, padding=1))
def forward(self, feat0, feat1, last_feat, last_flow):
corr_fn = correlation.FunctionCorrelation
feat0 = softsplat(
tenIn=feat0, tenFlow=last_flow[:, :2] * 0.25 * 0.5,
tenMetric=None, strMode='avg')
feat1 = softsplat(
tenIn=feat1, tenFlow=last_flow[:, 2:] * 0.25 * 0.5,
tenMetric=None, strMode='avg')
volume = F.leaky_relu(
input=corr_fn(tenFirst=feat0, tenSecond=feat1),
negative_slope=0.1, inplace=False)
input_feat = torch.cat([volume, feat0, feat1, last_feat, last_flow], 1)
feat = self.conv_layer1(input_feat)
feat = self.conv_layer2(feat)
feat = self.conv_layer3(feat)
feat = self.conv_layer4(feat)
feat = self.conv_layer5(feat)
flow = self.conv_layer6(feat)
return flow, feat
# **************************************************************************************************#
# => Frame Synthesis
# **************************************************************************************************#
class SynthesisNetwork(nn.Module):
def __init__(self, branch):
super(SynthesisNetwork, self).__init__()
self.branch = branch
input_channels = 9 + 4 + 6
self.encoder_conv = nn.Sequential(
nn.Conv2d(in_channels=input_channels, out_channels=64,
kernel_size=3, stride=1, padding=1),
nn.PReLU(num_parameters=64),
nn.Conv2d(in_channels=64, out_channels=64, kernel_size=3,
stride=1, padding=1),
nn.PReLU(num_parameters=64))
self.encoder_down1 = nn.Sequential(
nn.Conv2d(in_channels=64 + 32 + 32, out_channels=128,
kernel_size=3, stride=2, padding=1),
nn.PReLU(num_parameters=128),
nn.Conv2d(in_channels=128, out_channels=128, kernel_size=3,
stride=1, padding=1),
nn.PReLU(num_parameters=128),
nn.Conv2d(in_channels=128, out_channels=128, kernel_size=3,
stride=1, padding=1),
nn.PReLU(num_parameters=128))
self.encoder_down2 = nn.Sequential(
nn.Conv2d(in_channels=128 + 64 + 64, out_channels=256,
kernel_size=3, stride=2, padding=1),
nn.PReLU(num_parameters=256),
nn.Conv2d(in_channels=256, out_channels=256, kernel_size=3,
stride=1, padding=1),
nn.PReLU(num_parameters=256),
nn.Conv2d(in_channels=256, out_channels=256, kernel_size=3,
stride=1, padding=1),
nn.PReLU(num_parameters=256))
self.decoder_up1 = nn.Sequential(
torch.nn.ConvTranspose2d(in_channels=256 + 128 + 128,
out_channels=128, kernel_size=4, stride=2,
padding=1, bias=True),
nn.PReLU(num_parameters=128),
nn.Conv2d(in_channels=128, out_channels=128, kernel_size=3,
stride=1, padding=1),
nn.PReLU(num_parameters=128))
self.decoder_up2 = nn.Sequential(
torch.nn.ConvTranspose2d(in_channels=128 + 128,
out_channels=64, kernel_size=4, stride=2,
padding=1, bias=True),
nn.PReLU(num_parameters=64),
nn.Conv2d(in_channels=64, out_channels=64, kernel_size=3,
stride=1, padding=1),
nn.PReLU(num_parameters=64))
self.decoder_conv = nn.Sequential(
nn.Conv2d(in_channels=64 + 64, out_channels=64, kernel_size=3,
stride=1, padding=1),
nn.PReLU(num_parameters=64),
nn.Conv2d(in_channels=64, out_channels=64, kernel_size=3,
stride=1, padding=1),
nn.PReLU(num_parameters=64))
self.pred = nn.Conv2d(in_channels=64, out_channels=5, kernel_size=3,
stride=1, padding=1)
class MotionRefineNet(torch.nn.Module):
def __init__(self, branch):
super(MotionRefineNet, self).__init__()
self.branch = branch
self.img_pyramid = ImgPyramid()
self.motion_encdec = EncDec(branch)
def forward(self, flow0, flow1, im0, im1):
c0 = self.img_pyramid(im0)
c1 = self.img_pyramid(im1)
flow_res = self.motion_encdec(flow0, flow1, im0, im1, c0, c1)
flow0 = flow0.repeat(1, self.branch, 1, 1) + flow_res[0]
flow1 = flow1.repeat(1, self.branch, 1, 1) + flow_res[1]
return flow0, flow1, flow_res[2], flow_res[3]
self.MRN = MotionRefineNet(self.branch)
self.alpha = torch.nn.Parameter(torch.ones(1, 1, 1, 1))
# New params for splatting mask generation
self.alpha_splat_photo_consistency = torch.nn.Parameter(torch.ones(1, 1, 1, 1))
self.alpha_splat_flow_consistency = torch.nn.Parameter(torch.ones(1, 1, 1, 1))
self.alpha_splat_variation_flow = torch.nn.Parameter(torch.ones(1, 1, 1, 1))
def get_splat_weight(self, img0, img1, flow01, flow10):
M_splat = 1 / (1 + self.alpha_splat_photo_consistency * photometric_consistency(img0, img1, flow01)) + \
1 / (1 + self.alpha_splat_flow_consistency * flow_consistency(flow01, flow10)) + \
1 / (1 + self.alpha_splat_variation_flow * variance_flow(flow01))
return M_splat * self.alpha
def get_warped_representations(self, bi_flow, c0, c1, m_splat_0, m_splat_1,
i0=None, i1=None, time_period=0.5):
flow_0t = bi_flow[:, :2] * time_period
flow_1t = bi_flow[:, 2:4] * (1 - time_period)
warped_c0 = softsplat(
tenIn=c0, tenFlow=flow_0t,
tenMetric=m_splat_0, strMode='soft')
warped_c1 = softsplat(
tenIn=c1, tenFlow=flow_1t,
tenMetric=m_splat_1, strMode='soft')
if (i0 is None) and (i1 is None):
return warped_c0, warped_c1
else:
warped_img0 = softsplat(
tenIn=i0, tenFlow=flow_0t,
tenMetric=m_splat_0, strMode='soft')
warped_img1 = softsplat(
tenIn=i1, tenFlow=flow_1t,
tenMetric=m_splat_1, strMode='soft')
flow_0t_1t = torch.cat((flow_0t, flow_1t), 1)
return warped_img0, warped_img1, warped_c0, warped_c1, flow_0t_1t
def forward(self, last_i, i0, i1, c0_pyr, c1_pyr, bi_flow_pyr,
time_period=0.5, multi_flow=False):
m_splat_0_0 = self.get_splat_weight(i0, i1, bi_flow_pyr[0][:, :2], bi_flow_pyr[0][:, 2:4])
m_splat_1_0 = self.get_splat_weight(i1, i0, bi_flow_pyr[0][:, 2:4], bi_flow_pyr[0][:, :2])
if multi_flow:
tenFwd = bi_flow_pyr[0][:, :2]
tenBwd = bi_flow_pyr[0][:, 2:4]
tenFwd, tenBwd, WeiMF, WeiMB = self.MRN(tenFwd, tenBwd, i0, i1)
N_, _, H_, W_ = i0.shape
i0_ = i0.repeat(1, self.branch, 1, 1)
i1_ = i1.repeat(1, self.branch, 1, 1)
fltTime = time_period.repeat(1, self.branch, 1, 1)
tenFwd = tenFwd.reshape(N_, self.branch, 2, H_, W_).view(N_ * self.branch, 2, H_, W_)
tenBwd = tenBwd.reshape(N_, self.branch, 2, H_, W_).view(N_ * self.branch, 2, H_, W_)
WeiMF = WeiMF.reshape(N_, self.branch, 1, H_, W_).view(N_ * self.branch, 1, H_, W_)
WeiMB = WeiMB.reshape(N_, self.branch, 1, H_, W_).view(N_ * self.branch, 1, H_, W_)
i0_ = i0_.reshape(N_, self.branch, 3, H_, W_).view(N_ * self.branch, 3, H_, W_)
i1_ = i1_.reshape(N_, self.branch, 3, H_, W_).view(N_ * self.branch, 3, H_, W_)
fltTime = fltTime.reshape(N_, self.branch, 1, 1, 1).view(N_ * self.branch, 1, 1, 1)
tenPhotoone = self.get_splat_weight(i0_, i1_, tenFwd, tenBwd) * WeiMF
tenPhototwo = self.get_splat_weight(i1_, i0_, tenBwd, tenFwd) * WeiMB
t0 = fltTime
flow0 = tenFwd * t0
metric0 = tenPhotoone
t1 = 1.0 - fltTime
flow1 = tenBwd * t1
metric1 = tenPhototwo
flow0 = flow0.reshape(N_, self.branch, 2, H_, W_).permute(1, 0, 2, 3, 4)
flow1 = flow1.reshape(N_, self.branch, 2, H_, W_).permute(1, 0, 2, 3, 4)
metric0 = metric0.reshape(N_, self.branch, 1, H_, W_).permute(1, 0, 2, 3, 4)
metric1 = metric1.reshape(N_, self.branch, 1, H_, W_).permute(1, 0, 2, 3, 4)
i0_ = i0_.reshape(N_, self.branch, 3, H_, W_).permute(1, 0, 2, 3, 4)
i1_ = i1_.reshape(N_, self.branch, 3, H_, W_).permute(1, 0, 2, 3, 4)
t0 = t0.reshape(N_, self.branch, 1, 1, 1).permute(1, 0, 2, 3, 4)
t1 = t1.reshape(N_, self.branch, 1, 1, 1).permute(1, 0, 2, 3, 4)
tenOutputF, maskF, tenOutputB, maskB = forwarp_mframe_mask(i0_, flow0, t1, i1_, flow1, t0, metric0, metric1)
warped_img0 = tenOutputF + maskF * i0
warped_img1 = tenOutputB + maskB * i1
warped_c0, warped_c1 = \
self.get_warped_representations(
bi_flow_pyr[0], c0_pyr[0], c1_pyr[0], m_splat_0_0, m_splat_1_0,
time_period=time_period)
flow_0t = bi_flow_pyr[0][:, :2] * time_period
flow_1t = bi_flow_pyr[0][:, 2:4] * (1 - time_period)
flow_0t_1t = torch.cat((flow_0t, flow_1t), 1)
else:
warped_img0, warped_img1, warped_c0, warped_c1, flow_0t_1t = \
self.get_warped_representations(
bi_flow_pyr[0], c0_pyr[0], c1_pyr[0], m_splat_0_0, m_splat_1_0, i0, i1,
time_period=time_period)
input_feat = torch.cat(
(last_i, warped_img0, warped_img1, i0, i1, flow_0t_1t), 1)
s0 = self.encoder_conv(input_feat)
s1 = self.encoder_down1(torch.cat((s0, warped_c0, warped_c1), 1))
m_splat_0_1 = F.interpolate(m_splat_0_0, scale_factor=0.5, mode='bilinear')
m_splat_1_1 = F.interpolate(m_splat_1_0, scale_factor=0.5, mode='bilinear')
warped_c0, warped_c1 = self.get_warped_representations(
bi_flow_pyr[1], c0_pyr[1], c1_pyr[1], m_splat_0_1, m_splat_1_1,
time_period=time_period)
s2 = self.encoder_down2(torch.cat((s1, warped_c0, warped_c1), 1))
m_splat_0_2 = F.interpolate(m_splat_0_1, scale_factor=0.5, mode='bilinear')
m_splat_1_2 = F.interpolate(m_splat_1_1, scale_factor=0.5, mode='bilinear')
warped_c0, warped_c1 = self.get_warped_representations(
bi_flow_pyr[2], c0_pyr[2], c1_pyr[2], m_splat_0_2, m_splat_1_2,
time_period=time_period)
x = self.decoder_up1(torch.cat((s2, warped_c0, warped_c1), 1))
x = self.decoder_up2(torch.cat((x, s1), 1))
x = self.decoder_conv(torch.cat((x, s0), 1))
# prediction
refine = self.pred(x)
refine_res = torch.sigmoid(refine[:, :3]) * 2 - 1
refine_mask0 = torch.sigmoid(refine[:, 3:4])
refine_mask1 = torch.sigmoid(refine[:, 4:5])
merged_img = (warped_img0 * refine_mask0 * (1 - time_period) +
warped_img1 * refine_mask1 * time_period)
merged_img = merged_img / (refine_mask0 * (1 - time_period) +
refine_mask1 * time_period)
interp_img = merged_img + refine_res
interp_img = torch.clamp(interp_img, 0, 1)
extra_dict = {}
extra_dict["refine_res"] = refine_res
extra_dict["warped_img0"] = warped_img0
extra_dict["warped_img1"] = warped_img1
extra_dict["merged_img"] = merged_img
if multi_flow:
extra_dict['tenFwd'] = tenFwd.view(N_, self.branch, 2, H_, W_)
extra_dict['tenBwd'] = tenBwd.view(N_, self.branch, 2, H_, W_)
return interp_img, extra_dict
# **************************************************************************************************#
# => Unified model
# **************************************************************************************************#
@register('upr_net_multi_flow')
class UPRMultiFlow(nn.Module):
def __init__(self, pyr_level=3, nr_lvl_skipped=0, branch=1):
super(UPRMultiFlow, self).__init__()
self.pyr_level = pyr_level
self.feat_pyramid = FeatPyramid()
self.nr_lvl_skipped = nr_lvl_skipped
self.branch = branch
self.motion_estimator = MotionEstimator()
self.synthesis_network = SynthesisNetwork(self.branch)
def forward_one_lvl(self,
img0, img1, last_feat, last_flow, last_interp=None,
time_period=0.5, skip_me=False, multi_flow=False):
# context feature extraction
feat0_pyr = self.feat_pyramid(img0)
feat1_pyr = self.feat_pyramid(img1)
# bi-directional flow estimation
if not skip_me:
flow, feat = self.motion_estimator(
feat0_pyr[-1], feat1_pyr[-1],
last_feat, last_flow)
else:
flow = last_flow
feat = last_feat
# frame synthesis
## optical flow is estimated at 1/4 resolution
ori_resolution_flow = F.interpolate(
input=flow, scale_factor=4.0,
mode="bilinear", align_corners=False)
## consturct 3-level flow pyramid for synthesis network
bi_flow_pyr = []
tmp_flow = ori_resolution_flow
bi_flow_pyr.append(tmp_flow)
for i in range(2):
tmp_flow = F.interpolate(
input=tmp_flow, scale_factor=0.5,
mode="bilinear", align_corners=False) * 0.5
bi_flow_pyr.append(tmp_flow)
## merge warped frames as initial interpolation for frame synthesis
if last_interp is None:
flow_0t = ori_resolution_flow[:, :2] * time_period
flow_1t = ori_resolution_flow[:, 2:4] * (1 - time_period)
warped_img0 = softsplat(
tenIn=img0, tenFlow=flow_0t,
tenMetric=None, strMode='avg')
warped_img1 = softsplat(
tenIn=img1, tenFlow=flow_1t,
tenMetric=None, strMode='avg')
last_interp = warped_img0 * (1 - time_period) \
+ warped_img1 * time_period
## do synthesis
interp_img, extra_dict = self.synthesis_network(
last_interp, img0, img1, feat0_pyr, feat1_pyr, bi_flow_pyr,
time_period=time_period, multi_flow=multi_flow)
return flow, feat, interp_img, extra_dict
def forward(self, img0, img1, time_step,
pyr_level=None, nr_lvl_skipped=None, **kwargs):
if pyr_level is None: pyr_level = self.pyr_level
if nr_lvl_skipped is None: nr_lvl_skipped = self.nr_lvl_skipped
N, _, H, W = img0.shape
flow0_pred = []
flow1_pred = []
interp_imgs = []
skipped_levels = [] if nr_lvl_skipped == 0 else \
list(range(pyr_level))[::-1][-nr_lvl_skipped:]
# The original input resolution corresponds to level 0.
for level in list(range(pyr_level))[::-1]:
if level != 0:
scale_factor = 1 / 2 ** level
img0_this_lvl = F.interpolate(
input=img0, scale_factor=scale_factor,
mode="bilinear", align_corners=False)
img1_this_lvl = F.interpolate(
input=img1, scale_factor=scale_factor,
mode="bilinear", align_corners=False)
else:
img0_this_lvl = img0
img1_this_lvl = img1
# skip motion estimation, directly use up-sampled optical flow
skip_me = False
# the lowest-resolution pyramid level
if level == pyr_level - 1:
last_flow = torch.zeros(
(N, 4, H // (2 ** (level + 2)), W // (2 ** (level + 2)))
).to(img0.device)
last_feat = torch.zeros(
(N, 128, H // (2 ** (level + 2)), W // (2 ** (level + 2)))
).to(img0.device)
last_interp = None
# skip some levels for both motion estimation and frame synthesis
elif level in skipped_levels[:-1]:
continue
# last level (original input resolution), only skip motion estimation
elif (level == 0) and len(skipped_levels) > 0:
if len(skipped_levels) == pyr_level:
last_flow = torch.zeros(
(N, 4, H // 4, W // 4)).to(img0.device)
last_interp = None
else:
resize_factor = 2 ** len(skipped_levels)
last_flow = F.interpolate(
input=flow, scale_factor=resize_factor,
mode="bilinear", align_corners=False) * resize_factor
last_interp = F.interpolate(
input=interp_img, scale_factor=resize_factor,
mode="bilinear", align_corners=False)
skip_me = True
# last level (original input resolution), motion estimation + frame
# synthesis
else:
last_flow = F.interpolate(input=flow, scale_factor=2.0,
mode="bilinear", align_corners=False) * 2
last_feat = F.interpolate(input=feat, scale_factor=2.0,
mode="bilinear", align_corners=False)
last_interp = F.interpolate(
input=interp_img, scale_factor=2.0,
mode="bilinear", align_corners=False)
flow, feat, interp_img, extra_dict = self.forward_one_lvl(
img0_this_lvl, img1_this_lvl,
last_feat, last_flow, last_interp,
time_step, skip_me=skip_me, multi_flow=(level == 0))
if level != 0:
flow0_pred.append(
F.interpolate(input=flow[:, :2], scale_factor=4.0 * 2 ** level,
mode="bilinear", align_corners=False))
flow1_pred.append(
F.interpolate(input=flow[:, 2:], scale_factor=4.0 * 2 ** level,
mode="bilinear", align_corners=False))
else:
flow0_pred.append(extra_dict['tenFwd'])
flow1_pred.append(extra_dict['tenBwd'])
interp_imgs.append(F.interpolate(interp_img, scale_factor=2 ** level))
# directly up-sample estimated flow to full resolution with bi-linear
# interpolation
return {"imgt_preds": interp_imgs[-2:], "flow0_pred": flow0_pred[::-1], "flow1_pred": flow1_pred[::-1],
'imgt_pred': interp_img, "flowfwd": flow0_pred[-1][:, 0], "flowbwd": flow1_pred[-1][:, 0]}
if __name__ == "__main__":
pass
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