code: def matchBytes(self, bytes):
          
          p = self.position
          data = self[p:p + len(bytes)]
          rv = data.startswith(bytes)
          if rv:
              self.position += len(bytes)
          return rv
docs: Look for a sequence of bytes at the start of a string. If the bytes
          are found return True and advance the position to the byte after the
          match. Otherwise return False and leave the position alone