def forward(self, X: TT):
        """Linearly transform the row vectors in X.

        Arguments:
            X: a batch (matrix) of input vectors, one vector per row.
        Returns:
            A batch of output vectors (one vector per fow).
        """
        # Explicitely check that the dimensions match
        assert X.shape[1] == self.isize()
 
        return torch.mm(X, self.M.t())