function(vertex) {
      if (vertex.prev === null) {
        this.head = vertex.next;
      } else {
        vertex.prev.next = vertex.next;
      }

      if (vertex.next === null) {
        this.tail = vertex.prev;
      } else {
        vertex.next.prev = vertex.prev;
      }

      return this;
    }
function(vertex) {
      if (vertex.prev === null) {
        this.head = vertex.next;
      } else {
        vertex.prev.next = vertex.next;
      }

      if (vertex.next === null) {
        this.tail = vertex.prev;
      } else {
        vertex.next.prev = vertex.prev;
      }

      return this;
    }
function ( vertex ) { if ( vertex . prev === null ) { this . head = vertex . next ; } else { vertex . prev . next = vertex . next ; } if ( vertex . next === null ) { this . tail = vertex . prev ; } else { vertex . next . prev = vertex . prev ; } return this ; }
Removes a vertex from the linked list
Removes a vertex from the linked list