lib/command/list.js
function rpushx(key, value, req) {
  var val = this.getKey(key, req);
  if(val === undefined) {
    return 0;
  }
  return val.rpush([value]);
}
function rpushx(key, value, req) {
  var val = this.getKey(key, req);
  if(val === undefined) {
    return 0;
  }
  return val.rpush([value]);
}
function rpushx ( key , value , req ) { var val = this . getKey ( key , req ) ; if ( val === undefined ) { return 0 ; } return val . rpush ( [ value ] ) ; }
Insert values at the tail of the list stored at key
only if key exists.
Insert values at the tail of the list stored at key only if key exists .