def coerce(cls, string):
        """Create a :class:`Requirement` object from a given package spec."""
        match = re.match(cls.spec_regex, string)
        if not match:
            raise InvalidRequirementSpecError("could not parse requirement")
        package = match.group(1)
        if all(match.group(2, 3)):
            version = "".join(match.group(2, 3))
        else:
            version = None
        return cls(package, version)
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()