code: function isThenable(o) {
  		var _then, o_type = typeof o;
  
  		if (o != null &&
  			(
  				o_type == "object" || o_type == "function"
  			)
  		) {
  			_then = o.then;
  		}
  		return typeof _then == "function" ? _then : false;
  	}
docs: promise duck typing