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 _getProvenance(self, item, user, version=None, resource='item',
                       checkOk=True):
        params = {}
        if version is not None:
            params = {'version': version}
        resp = self.request(
            path='/%s/%s/provenance' % (resource, item['_id']),
            method='GET', user=user, type='application/json', params=params)
        if checkOk:
            self.assertStatusOk(resp)
        return resp