collapse

  Write a static method called collapse that takes an
   ArrayList of Strings as a parameter and that collapses successive pairs into
   a single String.  Each pair should be collapsed into a new String that has
   the two values inside parentheses and separated by a comma.  For example, if
   a variable called "list" initially stores these values:

	["four", "score", "and", "seven", "years", "ago"]

   and we make the following call:

        collapse(list);

   Your method should collapse the first pair into "(four, score)", the second
   pair into "(and, seven)" and the third pair into "(years, ago)" so that list
   stores the following values:

        ["(four, score)", "(and, seven)", "(years, ago)"]


   Notice that the list goes from having 6 elements to having 3 elements
   because each successive pair is collapsed into a single value.  If there are
   an odd number of values in the list, the final element is not collapsed.
   For example, if the original list had been:

	["to", "be", "or", "not", "to", "be", "hamlet"]

   It would again collapse pairs of values, but the final value ("hamlet")
   would not be collapsed, yielding this list:

        ["(to, be)", "(or, not)", "(to, be)", "hamlet"]

   Recall that the primary methods for manipulating an ArrayList are:

	add(E value)		 appends value at end of list
	add(int index, E value)	 inserts given value at given index, shifting
				 subsequent values right
	clear()			 removes all elements of the list
	get(int index)		 returns the value at given index
	remove(int index)	 removes and returns value at given index,
				 shifting subsequent values left
	set(int index, E value)	 replaces value at given index with given value
	size()			 returns the number of elements in list

   Write your solution to collapse below.