SeqItemType Sequence::retrieve(int index)
  {
 
   	if ((index < 1) || (index > size())){
   		// can't delete something that isn't there
   	}
   	ListNode *cur = find(index);
    return cur->item;	
  } 
 
 
 
   void Sequence::insert(int index, SeqItemType newItem)
  {
 
	if ((index < 1) || (index > (size()+1))){
   		// if index is out of bounds don't do anything
   	}
   	else
   	{  
   		// otherwise create new node and place newItem in it
      	ListNode *newPtr = new ListNode();
 
      	// increment the size attribute
      	length++;
        // store the data item in the new node
      	newPtr->item = newItem;
 
		//  if the index is 1, insert new node at beginning of list
        if (index == 1)
        { 
       		newPtr->next = head;
        	head = newPtr;
        }
        else
        {  
        	ListNode *prev = find(index-1);
        	newPtr->next = prev->next;
			prev->next = newPtr;
 
        }
	 } 
   }
 
 
void Sequence::remove(int index) 
{   
 
	ListNode *cur;
 
   	if ((index < 1) || (index > size())){
 
   		}
   	else
   	{  
		// remove the first node in the list
		if (index == 1)
      	{ 
      		cur = head;
     		head = head->next;   	
 
      	}
		else{
        	ListNode *prev = find(index-1);	
 
			cur = prev->next;
			prev->next = cur->next;
		}	
 
		// clean things up!
		length--;
		cur->next = NULL;
		delete cur;
	}
 
}
 
 
ListNode *Sequence::find(int index){
 
	if ((index <1) || (index >size())){
		return 0;
	}
	else{
		ListNode *cur = head;
		for(int skip =1; skip<index; ++skip)
			cur=cur->next;
		return cur;
  	}
}

void Sequence::move(int from, int to)
{
  SeqItemType item = find( from )->item ;
  remove(from) ;
  insert( to, item ) ;
}