apply method
Apply the given progress
level to the effect's target.
Here progress
is a variable that is typically in the range from 0 to 1,
with 0 being the initial state, and 1 the final state of the effect. See
EffectController for details.
This is a main method that MUST be implemented in every derived class.
Implementation
@override
void apply(double progress) {
if (progress == 1) {
target.removeFromParent();
}
}