@staticmethod
def apply_zoom(bsca, dval):
    """
        Apply a zoom action to CA class.

        :param bsca:
            :class:`xentica.core.CellularAutomaton` instance.
        :param dval:
            Delta by which the field is zoomed.

        """
    bsca.zoom = max(1, bsca.zoom + dval)
