def add(self, elem, replace=False):
        """Add a requirement.

        :param elem: a string or :class:`Requirement` instance.
        :param replace: if `True`, packages in the set with the same name will
            be removed first.
        """
        if isinstance(elem, text_type):
            elem = Requirement.coerce(elem)
        if replace and elem in self:
            self.remove(elem)
        super(Requirements, self).add(elem)
def draw(self, context):
        props = self.layout.operator("wm.context_set_value", text="Blender (default)")
        props.data_path = "window_manager.keyconfigs.active"
        props.value = "context.window_manager.keyconfigs.default"

        # now draw the presets
        Menu.draw_preset(self, context)