fix #143

            state['activation'] = F.relu

        super(CustomTransformerEncoderLayer, self).__setstate__(state)

    def forward(self, src: torch.Tensor, src_mask: Optional[torch.Tensor] = None, src_key_padding_mask: Optional[torch.Tensor] = None) -> torch.Tensor:

    def forward(self, src: torch.Tensor, src_mask: Optional[torch.Tensor] = None, src_key_padding_mask: Optional[torch.Tensor] = None, is_causal = None) -> torch.Tensor:

        r"""Pass the input through the encoder layer.

        Args:

            src: the sequence to the encoder layer (required).