from operator import concat


def CreateStorageKey(s1, s2):
    """Concatenate arguments for use as storage key.
    
    Args:
        s1 (str):
            first string to be used in concatenation.
        s2 (str):
            second string to be used in concatenation.
    Return:
        (str): args concatenated together with a '.' between each value.
    """

    withPeriod = concat(s1, '.')
    return concat(withPeriod, s2)