Returns true when one national number is the suffix of the other or both
    are the same.

def _is_national_number_suffix_of_other(numobj1, numobj2):
    """Returns true when one national number is the suffix of the other or both
    are the same.
    """
    nn1 = str(numobj1.national_number)
    nn2 = str(numobj2.national_number)
    # Note that endswith returns True if the numbers are equal.
    return nn1.endswith(nn2) or nn2.endswith(nn1)