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 _init_gui(self):
    self._size_spin_button = gtk.SpinButton(
      gtk.Adjustment(
        value=0,
        lower=self._min_size,
        upper=self._max_size,
        step_incr=1,
        page_incr=10,
      ),
      digits=0)