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 _safe_close(self, sess):
    """Closes a session without raising an exception.

    Just like sess.close() but ignores exceptions.

    Args:
      sess: A `Session`.
    """
    # pylint: disable=broad-except
    try:
      sess.close()
    except Exception:
      # Intentionally not logging to avoid user complaints that
      # they get cryptic errors.  We really do not care that Close
      # fails.
      pass
    # pylint: enable=broad-except