∀ {reason : Option Std.CancellationReason} {consumers : Std.Queue Std.CancellationToken.Consumer}
  {reason_1 : Option Std.CancellationReason} {consumers_1 : Std.Queue Std.CancellationToken.Consumer},
  { reason := reason, consumers := consumers } = { reason := reason_1, consumers := consumers_1 } →
    reason = reason_1 ∧ consumers = consumers_1