call is just the method used to call other methods, not very usefull tbh, you can call the method directly.
node.call("method") is identical to
call_deferred() is instead more useful, as it will call a method only during idle time (meaning it will wait till "normal" code execution will be finished, and then call the requested method)
i'm not 100% sure why the docs tells you to call the method
do using this complex form, instead of simply calling
The use i can think of is controlling which method to trigger by the use of a string, eg:
in the child node:
in the parent node:
with this kind of structure you can control which method will be called during the process of the child, by changing the value of the string x.
In this case it will print "hello" at every process frame.