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 _ui_font_style(layout, font_style):

        split = layout.split()

        col = split.column()
        col.label(text="Kerning Style:")
        col.row().prop(font_style, "font_kerning_style", expand=True)
        col.prop(font_style, "points")

        col = split.column()
        col.label(text="Shadow Offset:")
        col.prop(font_style, "shadow_offset_x", text="X")
        col.prop(font_style, "shadow_offset_y", text="Y")

        col = split.column()
        col.prop(font_style, "shadow")
        col.prop(font_style, "shadow_alpha")
        col.prop(font_style, "shadow_value")

        layout.separator()