setProperty(child, key, value, operation, force) → {boolean}
Sets a property to the given value on the child. The operation parameter controls how the value is set. The operations are: 0: set the existing value to the given value; if force is true a new property will be created if needed 1: will add the given value to the value already present. 2: will subtract the given value from the value already present. 3: will multiply the value already present by the given value. 4: will divide the val