code: def append(self, filename, content, binary=False):
          
  
          self._raise_if_none()
          fn = path_join(self.path, filename)
  
          if binary:
              flags = 'ab'
          else:
              flags = 'a'
  
          with open(fn, 'a') as f:
              f.write(content)
              return True
docs: Appends given content to given filename.