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 signal_handler_mapping(self):
        """A dict mapping (signal number) -> (a method handling the signal)."""
        # Could use an enum here, but we never end up doing any matching on the specific signal value,
        # instead just iterating over the registered signals to set handlers, so a dict is probably
        # better.
        return {
            signal.SIGINT: self._handle_sigint_if_enabled,
            signal.SIGQUIT: self.handle_sigquit,
            signal.SIGTERM: self.handle_sigterm,
        }