human
I wrote the below code

    if (not ((relative_to is None) or isinstance(relative_to, types.ModuleType) or (isinstance(relative_to, type) and issubclass(relative_to, Message)))):
        raise TypeError(('relative_to    must    be    None,    Message    definition    or    module.        Found:    %s' % relative_to))
    name_path = name.split('.')
    if (not name_path[0]):
        relative_to = None
        name_path = name_path[1:]
    def search_path():
        'Performs    a    single    iteration    searching    the    path    from    relative_to.\n\n                This    is    the    function    that    searches    up    the    path    from    a    relative    object.\n\n                        fully.qualified.object    .    relative.or.nested.Definition\n                                                                                                                            ---------------------------->\n                                                                                                                                                                                                        ^\n                                                                                                                                                                                                        |\n                                                                                                                this    part    of    search    --+\n\n                Returns:\n                        Message    or    Enum    at    the    end    of    name_path,    else    None.\n                '
        next = relative_to
        for node in name_path:
            attribute = getattr(next, node, None)
            if (attribute is not None):
                next = attribute
            elif ((next is None) or isinstance(next, types.ModuleType)):
                if (next is None):
                    module_name = node
                else:
                    module_name = ('%s.%s' % (next.__name__, node))
               ...

What's a good function header?
 ... Here's a good function header?
assistant
#Here's a good function header.

@util.positional(2)
def find_definition(name, relative_to=None, importer=__import__):