def __init__(self, package, version):
        """Construct a new requirement.

        :param package: the package name.
        :param version: a semver compatible version specification.
        """
        self.package = package
        self.version = version
        if self.version and not re.match(r"[<=>~]", version[:2]):
            self.version = "=={}".format(self.version)
def deserialize(self, value):
        value = decode(value).strip()
        expanded = path.expand_path(value)
        validators.validate_required(value, self._required)
        validators.validate_required(expanded, self._required)
        if not value or expanded is None:
            return None
        return _ExpandedPath(value, expanded)