src/event.js
function deleteListener(event, callback, idx) {
  if ((idx = event.listeners.indexOf(callback)) >= 0) {
    event.listeners.splice(idx, 1);
    event.meta.delete(callback);
    return true;
  }
  return false;
}
function deleteListener(event, callback, idx) {
  if ((idx = event.listeners.indexOf(callback)) >= 0) {
    event.listeners.splice(idx, 1);
    event.meta.delete(callback);
    return true;
  }
  return false;
}
function deleteListener ( event , callback , idx ) { if ( ( idx = event . listeners . indexOf ( callback ) ) >= 0 ) { event . listeners . splice ( idx , 1 ) ; event . meta . delete ( callback ) ; return true ; } return false ; }
Delete event listener returns true on success

@param {Object} event
@param {Function} callback
@param {number} [idx]
@returns {boolean}
Delete event listener returns true on success