def _add_raise_message(self, missing_excs, node):
if node.is_abstract():<EOL><INDENT>try:<EOL><INDENT>missing_excs.remove("<STR_LIT>")<EOL><DEDENT>except KeyError:<EOL><INDENT>pass<EOL><DEDENT><DEDENT>if not missing_excs:<EOL><INDENT>return<EOL><DEDENT>self.add_message(<EOL>"<STR_LIT>", args=("<STR_LIT:U+002CU+0020>".join(sorted(missing_excs)),), node=node<EOL>)<EOL>
Adds a message on :param:`node` for the missing exception type.

:param missing_excs: A list of missing exception types.
:type missing_excs: set(str)

:param node: The node show the message on.
:type node: astroid.node_classes.NodeNG