Godot - Change Tween playback speed

GDScript code example to change Tween playback speed.

set_speed_scale() can change playback speed of a Tween whether stopped or playing.
Specify multiplier number value as argument for set_speed_scale().

Specify "1" to return to original speed.
set_speed_scale() cannot specify an empty value.

var tween = create_tween().set_loops()
tween.tween_property(self, "modulate", Color( 1, 1, 1, 0), 0.5)
tween.tween_property(self, "modulate", Color( 1, 1, 1, 1), 0.5).set_delay(0.5)
tween.play()

tween.set_speed_scale(2.0)