# Retrieve the associated AST node of a mclassdef.
	#
	# This method is used to associate model entity with syntactic entities.
	# If the class definition is not associated with a node, returns `null`.
	fun mclassdef2node(mclassdef: MClassDef): nullable AClassdef do
		return mclassdef2nclassdef.get_or_null(mclassdef)
	end