code: def checkstyle(self, sources):
      
      failure_count = 0
      for filename in sources:
        failure_count += self._check_file(filename)
      return failure_count
docs: Iterate over sources and run checker on each file.
  
      Files can be suppressed with a --suppress option which takes an xml file containing
      file paths that have exceptions and the plugins they need to ignore.
  
      :param sources: iterable containing source file names.
      :return: (int) number of failures