import re


def normalize_response_key(key: str) -> str:
    """
    Convert camel case `ParamA` to snake case `param_a`
    """
    split = re.findall(r'[A-Z](?:[a-z]+|[A-Z]*(?=[A-Z]|$))', key)
    if split:
        return '_'.join([val.lower() for val in split])
    return key.lower()