Updated links to point to dev documentation.

            module = import_module(module_name)

            if not hasattr(module, value.__name__):

                raise ValueError(

                    "Could not find function %s in %s.\nPlease note that "

                    "due to Python 2 limitations, you cannot serialize "

                    "unbound method functions (e.g. a method declared\n"

                    "and used in the same class body). Please move the "

                    "function into the main module body to use migrations.\n"

                    "For more information, see https://docs.djangoproject.com/en/1.7/topics/migrations/#serializing-values"

                    "Could not find function %s in %s.\n"

                    "Please note that due to Python 2 limitations, you cannot "

                    "serialize unbound method functions (e.g. a method "

                    "declared and used in the same class body). Please move "

                    "the function into the main module body to use migrations.\n"

                    "For more information, see "

                    "https://docs.djangoproject.com/en/dev/topics/migrations/#serializing-values"

                    % (value.__name__, module_name))

            return "%s.%s" % (module_name, value.__name__), set(["import %s" % module_name])

        # Classes