code: def _parse(coord, _match=_regex.match):
          
          try:
              return _match(coord).groups()
          except AttributeError:
              raise ValueError(coord)
docs: Return match groups from single sheet coordinate.
  
          >>> Coordinates._parse('A1')
          ('A', '1', None, None)
  
          >>> Coordinates._parse('A'), Coordinates._parse('1')
          ((None, None, 'A', None), (None, None, None, '1'))
  
          >>> Coordinates._parse('spam')
          Traceback (most recent call last):
              ...
          ValueError: spam