docs: def run(self):
          """Run analysis on a single file."""
          pydocstyle.Error.explain = self.options['explain']
          filename, source = load_file(self.filename)
          for error in pydocstyle.PEP257Checker().check_source(source, filename):
              if not hasattr(error, 'code') or ignore(error.code):
                  continue
              lineno = error.line
              offset = 0  # Column number starting from 0.
              explanation = error.explanation if pydocstyle.Error.explain else ''
              text = '{0} {1}{2}'.format(error.code, error.message.split(': ', 1)[1], explanation)
              yield lineno, offset, text, Main