remove(val){
    if(this.head === null) {
      return -1;
    }
    else if(this.head.val === val) {
      this.head = this.head.next;
      return 1;
    }
    let read = this.head;
    while(read.next !== null){
      if(read.next.val === val){
        read.next = read.next.next;
        return 1;
      }
    }
    return -1;
  }