@abc.abstractmethod<EOL><INDENT>def set_principal_credit_string(self, credit_string):<DEDENT>
pass<EOL>
Sets the principal credit string.

        :param credit_string: the new credit string
        :type credit_string: ``string``
        :raise: ``InvalidArgument`` -- ``credit_string`` is invalid
        :raise: ``NoAccess`` -- ``Metadata.isReadOnly()`` is ``true``
        :raise: ``NullArgument`` -- ``credit_string`` is ``null``

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