code: def _GenerateSection(self, problem_type):
      
      if problem_type == transitfeed.TYPE_WARNING:
        dataset_problems = self._dataset_warnings
        heading = 'Warnings'
      else:
        dataset_problems = self._dataset_errors
        heading = 'Errors'
  
      if not dataset_problems:
        return ''
  
      prefix = '<h2 class="issueHeader">%s:</h2>' % heading
      dataset_sections = []
      for dataset_merger, problems in dataset_problems.items():
        dataset_sections.append('<h3>%s</h3><ol>%s</ol>' % (
            dataset_merger.FILE_NAME, '\n'.join(problems)))
      body = '\n'.join(dataset_sections)
      return prefix + body
docs: Generate a listing of the given type of problems.
  
      Args:
        problem_type: The type of problem. This is one of the problem type
                      constants from transitfeed.
  
      Returns:
        The generated HTML as a string.