Constructs a message that, when send to Replicator, will perform an update of a structure stored under provided key. Update operation is described by modify function, that will take a previous value as an input parameter. An consistency level may be provided to set up certain constraints on retrieved IUpdateResponse replied from replicator as a result.

public static Update Update<T>(
	IKey<T> key,
	IWriteConsistency consistency,
	Func<T, T> modify
)
where T : IReplicatedData

static member Update : 
        key : IKey<'T> * 
        consistency : IWriteConsistency * 
        modify : Func<'T, 'T> -> Update  when 'T : IReplicatedData