Set the value of the ref to update
if the current value is expect
,
returns whether the value was updated.
Returns the current value of the ref.
Atomically updates the ref with the result of applying the given function to the current value, returning the updated value.
Atomically updates the ref with the first part of the result of applying the given function to the current value, returning the second part.
Sets the value of the ref to the given value.