function vibrateNumber(num) {
  return new Promise(function f(resolve){
    if (!num.length) return resolve();
    var digit = num[0];
    num = num.substr(1);
    vibrateDigit(digit).then(()=>{
      setTimeout(()=>f(resolve),500);
    });
  });
}
// vibrate multiple digits (num must be a string)
vibrate multiple digits (num must be a string)
vibrate multiple digits ( num must be a string )
function vibrateNumber(num) {
  return new Promise(function f(resolve){
    if (!num.length) return resolve();
    var digit = num[0];
    num = num.substr(1);
    vibrateDigit(digit).then(()=>{
      setTimeout(()=>f(resolve),500);
    });
  });
}
function vibrateNumber ( num ) { return new Promise ( function f ( resolve ) { if ( ! num . length ) return resolve ( ) ; var digit = num [ 0 ] ; num = num . substr ( 1 ) ; vibrateDigit ( digit ) . then ( ( ) => { setTimeout ( ( ) => f ( resolve ) , 500 ) ; } ) ; } ) ; }
vibrate multiple digits (num must be a string)
vibrate multiple digits ( num must be a string )