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 _on_item_widget_key_press_event(self, widget, event, item):
    if event.state & gtk.gdk.MOD1_MASK:     # Alt key
      key_name = gtk.gdk.keyval_name(event.keyval)
      if key_name in ["Up", "KP_Up"]:
        self.reorder_item(
          item, self._get_item_position(item) - 1)
      elif key_name in ["Down", "KP_Down"]:
        self.reorder_item(
          item, self._get_item_position(item) + 1)