code: def _check_std(self, paths, cmd_pieces):
          
          cmd_pieces.extend(paths)
          process = Popen(cmd_pieces, stdout=PIPE, stderr=PIPE)
          out, err = process.communicate()
          lines = out.strip().splitlines() + err.strip().splitlines()
          result = []
          for line in lines:
              match = self.tool_err_re.match(line)
              if not match:
                  if self.break_on_tool_re_mismatch:
                      raise ValueError(
                          'Unexpected `%s` output: %r' % (
                              ' '.join(cmd_pieces),
                              paths,
                              line))
                  continue
              vals = match.groupdict()
  
              # All tools should at least give us line numbers, but only
              # some give column numbers.
              vals['lineno'] = int(vals['lineno'])
              vals['colno'] = \
                  int(vals['colno']) if vals['colno'] is not None else ''
  
              result.append(vals)
          return result
docs: Run `cmd` as a check on `paths`.