@abc.abstractmethod<EOL><INDENT>def get_trusts(self):<DEDENT>
return<EOL>
Gets all ``Trusts``.

        In plenary mode, the returned list contains all known trusts or
        an error results. Otherwise, the returned list may contain only
        those trusts that are accessible through this session.

        :return: a list of ``Trusts``
        :rtype: ``osid.authentication.process.TrustList``
        :raise: ``OperationFailed`` -- unable to complete request
        :raise: ``PermissionDenied`` -- authorization failure

        *compliance: mandatory -- This method must be implemented.*