sum(dim = null, keepdim = false) {
        return this.norm(1, dim, keepdim);
    }
Returns the sum of each row of the input tensor in the given dimension dim.

@param {number} [dim=null] The dimension or dimensions to reduce. If `null`, all dimensions are reduced.
@param {boolean} keepdim Whether the output tensor has `dim` retained or not.
@returns The summed tensor