docs: def scan(self, regex):
          """
          Match a pattern from the current position.
  
          If a match is found, advances the scan pointer and returns the matched
          string. Otherwise returns ``None``.
  
              >>> s = Scanner("test string")
              >>> s.pos
              0
              >>> s.scan(r'foo')
              >>> s.scan(r'bar')
              >>> s.pos
              0
              >>> s.scan(r'test ')
              'test '
              >>> s.pos
              5
          """
          return self.scan_full(regex, return_string=True, advance_pointer=True)