    def forward(self, src):
        """Pass the input through the endocder layers in turn.
        Args:
            src: the sequnce to the encoder (required).
            mask: the mask for the src sequence (optional).
            src_key_padding_mask: the mask for the src keys per batch (optional).
        """
        output = src

        for i in range(self.num_layers):
            output = self.layers[i](output,
                                    src_mask=None,
                                    src_key_padding_mask=None)

        return output
Pass the input through the endocder layers in turn.
Args:
src: the sequnce to the encoder (required).
mask: the mask for the src sequence (optional).
src_key_padding_mask: the mask for the src keys per batch (optional).
pytorchocr/modeling/heads/rec_nrtr_head.py