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 _match_less_than(search_base, attribute, value, candidates):
        matches = list()
        for entry in candidates:
            dn = entry.get("dn")
            if not dn.endswith(search_base):
                continue

            value_from_directory = entry.get("attributes").get(attribute)
            if str(value_from_directory) < str(value):
                entry["type"] = "searchResEntry"
                matches.append(entry)

        return matches