State of a function call after yielding.
Calling [method @GDScript.yield] within a function will cause that function to yield and return its current state as an object of this type. The yielded function call can then be resumed later by calling [method resume] on this state object.
Check whether the function call may be resumed. This is not the case if the function state was already resumed. If [code]extended_check[/code] is enabled, it also checks if the associated script and object still exist. The extended check is done in debug mode as part of [method GDFunctionState.resume], but you can use this if you know you may be trying to resume without knowing for sure the object and/or script have survived up to that point.
Resume execution of the yielded function call. If handed an argument, return the argument from the [method @GDScript.yield] call in the yielded function call. You can pass e.g. an [Array] to hand multiple arguments. This function returns what the resumed function call returns, possibly another function state if yielded again.