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 delete_snapshot_metadata_item(self, snapshot_id, id):
        """Delete metadata item for the snapshot."""
        url = "snapshots/%s/metadata/%s" % (str(snapshot_id), str(id))
        resp, body = self.delete(url)
        return resp, body