def set_epoch(self, epoch):
        """Set the epoch for the current GPS scale.

        This method will fail if the current X-axis scale isn't one of
        the GPS scales. See :ref:`gwpy-plot-gps` for more details.

        Parameters
        ----------
        epoch : `float`, `str`
            GPS-compatible time or date object, anything parseable by
            :func:`~gwpy.time.to_gps` is fine.
        """
        scale = self.get_xscale()
        return self.set_xscale(scale, epoch=epoch)
Set the epoch for the current GPS scale.

        This method will fail if the current X-axis scale isn't one of
        the GPS scales. See :ref:`gwpy-plot-gps` for more details.

        Parameters
        ----------
        epoch : `float`, `str`
            GPS-compatible time or date object, anything parseable by
            :func:`~gwpy.time.to_gps` is fine.