docs: def file_contents(self, filename, binary=False):
          """Return the file for a given filename.
  
          If you want binary content use ``mode='rb'``.
  
          """
          if binary:
              mode = 'rb'
          else:
              mode = 'r'
          try:
              with open(filename, mode) as f:
                  return f.read()
          except (OSError, IOError) as e:
              raise FileReadError(str(e))