def add_accessibility_type(self, accessibility_type=None):
if accessibility_type is None:<EOL><INDENT>raise NullArgument()<EOL><DEDENT>metadata = Metadata(**settings.METADATA['<STR_LIT>'])<EOL>if metadata.is_read_only():<EOL><INDENT>raise NoAccess()<EOL><DEDENT>if self._is_valid_input(accessibility_type, metadata, array=False):<EOL><INDENT>self._my_map['<STR_LIT>'].append(accessibility_type._my_map['<STR_LIT:id>'])<EOL><DEDENT>else:<EOL><INDENT>raise InvalidArgument<EOL><DEDENT>
Adds an accessibility type.

        Multiple types can be added.

        :param accessibility_type: a new accessibility type
        :type accessibility_type: ``osid.type.Type``
        :raise: ``InvalidArgument`` -- ``accessibility_type`` is invalid
        :raise: ``NoAccess`` -- ``Metadata.isReadOnly()`` is ``true``
        :raise: ``NullArgument`` -- ``accessibility_t_ype`` is ``null``

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