undouble

  Write a static method called undouble that takes a
   string as a parameter and that returns a new string obtained by replacing
   every pair of repeated adjacent letters with one of that letter.  For
   example, the String "bookkeeper" has three repeated adjacent letters ("oo",
   "kk", and "ee"), so undouble("bookkeeper") should return the string
   "bokeper".  Below are more sample calls:

        Method                   Value        Method                  Value
         Call                   Returned       Call                  Returned
        ---------------------------------    ---------------------------------
	undouble("odegaard")    "odegard"    undouble("oops")	     "ops"
	undouble("baz")		"baz"	     undouble("foobar")	     "fobar"
	undouble("mississippi") "misisipi"   undouble("apple")	     "aple"
	undouble("carry")	"cary"	     undouble("berry")	     "bery"
	undouble("juggle")	"jugle"	     undouble("theses")	     "theses"
	undouble("little")	"litle"	     undouble("")	     ""

   You may assume that the string is composed entirely of lowercase letters, as
   in the examples above, and that no letter appears more than two times in a
   row.  But notice that the method might be passed an empty string, in which
   case it returns an empty string.