The main entry point for checking access to AFF4 resources.

    Args:
      token: An instance of ACLToken security token.

      subjects: The list of subject URNs which the user is requesting access
         to. If any of these fail, the whole request is denied.

      requested_access: A string specifying the desired level of access ("r" for
         read and "w" for write, "q" for query).

    Raises:
       UnauthorizedAccess: If the user is not authorized to perform the action
       on any of the subject URNs.

def CheckDataStoreAccess(self, token, subjects, requested_access="r"):
    """The main entry point for checking access to AFF4 resources.

    Args:
      token: An instance of ACLToken security token.

      subjects: The list of subject URNs which the user is requesting access
         to. If any of these fail, the whole request is denied.

      requested_access: A string specifying the desired level of access ("r" for
         read and "w" for write, "q" for query).

    Raises:
       UnauthorizedAccess: If the user is not authorized to perform the action
       on any of the subject URNs.
    """
    logging.debug("Checking %s: %s for %s", token, subjects, requested_access)
    raise NotImplementedError()