def three_to_one_standard()

in pdb_parse.py [0:0]

• 4 lines of code
• 2 McCabe index (conditional complexity)

def three_to_one_standard(res: Residue) -> str:
    """Encode non-standard AA to X."""
    if not is_aa(res, standard=True):
        return "X"
    return three_to_one(res)