code: def skip(self, content):
          
          if self.optional(content):
              v = content.value
              if v is None:
                  return True
              if isinstance(v, (list, tuple)) and not v:
                  return True
          return False
docs: Get whether to skip this I{content}.
  
          Should be skipped when the content is optional and value is either None
          or an empty list.
  
          @param content: Content to skip.
          @type content: L{Object}
          @return: True if content is to be skipped.
          @rtype: bool