lo to 0 and hi to the last index of the array.lo is less than hi:
a. Calculate mid as the midpoint of lo and hi.
b. If mid is odd, decrement it by 1 to ensure it is even.
c. If the element at mid is equal to the element at mid + 1, set lo to mid + 2.
d. Otherwise, set hi to mid.lo equals hi, the element at this index is the single element. Return it.