docs: def _init_append(self):
          """
          Initializes file on 'a' mode.
          """
          if self._content_length:
              # Adjust size if content length specified
              with _handle_azure_exception():
                  self._resize(
                      content_length=self._content_length, **self._client_kwargs)
                  self._reset_head()
  
          # Make initial seek position to current end of file
          self._seek = self._size