signals

 have you looked at this one? https://github.com/godotengine/godot/wiki/gdscript#signals
<kubecz3k> basically in the node that emit signal you need to declare signal with signal keyword
* PLyczkowski (~quassel@89-65-89-170.dynamic.chello.pl) has joined
<kubecz3k> then you can connect from editor gui or with command: get_node(path_2_node_with_registered_signal).connect("your_signal_name",self,"callback_no_args")
<kubecz3k> and emit with emit("your_signal_name") (from that node that have signal declaration)