'Parse a menufile for node functions and store in dictionary
map. Alternatively, accept a pre-made mapping dictionary of
node functions.
Args:
menudata (str, module or dict): The python.path to the menufile,
or the python module itself. If a dict, this should be a
mapping nodename:callable, where the callable must match
the criteria for a menu node.
Returns:
menutree (dict): A {nodekey: func}'

def _parse_menudata(self, menudata):

    if isinstance(menudata, dict):
        return menudata
    else:
        module = mod_import(menudata)
        return dict(((key, func) for (key, func) in module.__dict__.items() if (isfunction(func) and (not key.startswith('_')))))
