in src/mozanalysis/frequentist_stats/linear_models/functions.py [0:0]
def _infer_branch_list(branches: pd.Series, branch_list: list[str] | None) -> list[str]:
"""Determine the list of distinct branches. Used so that `summarize_univariate`
and `summarize_joint` can take an optional `branch_list` parameter."""
if branch_list:
return branch_list
return list(branches.unique())