The Unsorted List ADT is to be extended with a Boolean member function, IsThere, which takes as a parameter an item of type ItemType and determines whether there is an element with this key in the list. 1. Write the specifications for this function. 2. Write the prototype for this function. 3. Write the function definition using an array-based implementation. 4. Write the function definition using a linked implementation. 5. Describe this function in terms of Big-O.