path/to/venv/lib/python3.10/site-packages/fontTools/feaLib/lookupDebugInfo.py

from typing import NamedTuple

LOOKUP_DEBUG_INFO_KEY = "com.github.fonttools.feaLib"
LOOKUP_DEBUG_ENV_VAR = "FONTTOOLS_LOOKUP_DEBUGGING"


class LookupDebugInfo(NamedTuple):
    """Information about where a lookup came from, to be embedded in a font"""

    location: str
    name: str
    feature: list