Given a string, return a new string made of $3$ copies of the last $2$ chars of the original string. The string length will be at least $2.$

extra$\_$end$(\text{'}$Hello$\text{'})->$ 'lololo'

extra$\_$end$(\text{'}$ab$\text{'})->$ 'ababab'

extra$\_$end$(\text{'}$Hi$\text{'})->$ 'HiHiHi'