def remove(self, elem):
        """Remove a requirement.

        :param elem: a string or :class:`Requirement` instance.
        """
        if isinstance(elem, text_type):
            for requirement in self:
                if requirement.package == elem:
                    return super(Requirements, self).remove(requirement)
        return super(Requirements, self).remove(elem)
def _theme_widget_style(layout, widget_style):

        row = layout.row()

        subsplit = row.split(percentage=0.95)

        padding = subsplit.split(percentage=0.15)
        colsub = padding.column()
        colsub = padding.column()
        colsub.row().prop(widget_style, "outline")
        colsub.row().prop(widget_style, "item", slider=True)
        colsub.row().prop(widget_style, "inner", slider=True)
        colsub.row().prop(widget_style, "inner_sel", slider=True)

        subsplit = row.split(percentage=0.85)

        padding = subsplit.split(percentage=0.15)
        colsub = padding.column()
        colsub = padding.column()
        colsub.row().prop(widget_style, "text")
        colsub.row().prop(widget_style, "text_sel")
        colsub.prop(widget_style, "show_shaded")
        subsub = colsub.column(align=True)
        subsub.active = widget_style.show_shaded
        subsub.prop(widget_style, "shadetop")
        subsub.prop(widget_style, "shadedown")

        layout.separator()