{Actor}.modifyActorVar(name, value)

USE: 
Use this function to modify the float value of a variable by a given value. 
The actor can be the Player or any other actor.

This function was introduced with LifePlay 2.18.

TYPE: Command, Non-Ref (ref-like syntax)
RETURNS: /
THEME: Variables
COMPARE: getActorVar, modifyActorVar

EXAMPLE:
    Player.setActorVar(SomeVariable, 42)     // Set the variable to 42
    Player.modifyActorVar(SomeVariable, 1)
    val = Player.getActorVar(SomeVariable)
    "The value of SomeVariable is <val>."   // Will be 43
    
    Player.modifyActorVar(SomeVariable, -30)
    val = Player.getActorVar(SomeVariable)
    "The value of SomeVariable is <val>."   // Will be 13