node_Script.py

def update_py(self):
    '''
    triggered when update is called, ideally this
    - runs script with default values for those in_sockets not connected
    - does nothing if input is unchanged.
    '''
    node_function = self.node_dict[hash(self)].get('node_function', None)
    if not node_function:
        return

    defaults = node_function.__defaults__
    input_names = [i.name for i in self.inputs]

    fparams = []
    for param_idx, name in enumerate(input_names):
        links = self.inputs[name].links
        this_val = defaults[param_idx]

        if links:
            # for now it is necessary type check these, it's a bit more code
            # but allows for nested lists.
            if isinstance(this_val, (int, float)):
                k = str(SvGetSocketAnyType(self, self.inputs[param_idx]))
                kfree = k[2:-2]
                this_val = ast.literal_eval(kfree)

            elif isinstance(this_val, list):
                this_val = self.inputs[param_idx].sv_get()[0]

        fparams.append(this_val)

    if node_function and (len(fparams) == len(input_names)):

        fn_return_values = node_function(*fparams)
        out_sockets = fn_return_values[1]

        for socket_type, name, data in out_sockets:
            SvSetSocketAnyType(self, name, data)