ZoneBinaryCallback bindBinaryCallback<R, T1, T2>(R action(T1 argument1, T2 argument2), { bool runGuarded: true })

Equivalent to:

 ZoneCallback registered = registerBinaryCallback(action);
 if (runGuarded) {
   return (arg1, arg2) => this.runBinaryGuarded(registered, arg);
 }
 return (arg1, arg2) => thin.runBinary(registered, arg1, arg2);

Source 

ZoneBinaryCallback<R, T1, T2> bindBinaryCallback<R, T1, T2>(
    R action(T1 argument1, T2 argument2),
    { bool runGuarded: true });