def METHOD_NAME(self, x: Float[Array, "... D"]) -> Float[Array, "... Q"]:
    r"""Slice out the relevant columns of the input matrix.
    Select the relevant columns of the supplied matrix to be used within the
    kernel's evaluation.
    Args:
        x (Float[Array, "... D"]): The matrix or vector that is to be sliced.
    Returns
    -------
        Float[Array, "... Q"]: A sliced form of the input matrix.
    """
    return x[..., self.active_dims] if self.active_dims is not None else x