code: def input_file(self, filename, lines=None, expected=None, line_offset=0):
          
          if self.options.verbose:
              print('checking %s' % filename)
          fchecker = self.checker_class(
              filename, lines=lines, options=self.options)
          return fchecker.check_all(expected=expected, line_offset=line_offset)
docs: Run all checks on a Python source file.