input: def match_numeric_strings(strings: List[str]) -> List[bool]:
      """Given a list of strings, return a list of booleans where each boolean indicates 
      whether the corresponding string in the input list is a numeric string (consisting 
      only of digits).
      >>> match_numeric_strings(['123456789', 'abc123', '987654', ''])
      [True, False, True, False]
      """
output:     return [s.isdigit() for s in strings]