String$-1>$ make$\_$abba

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Given two strings, a and b$,$ return the result of putting them together in the order abba, e$.$g$."$Hi$"$ and "Bye" returns "HiByeByeHi".

make$\_$abba$(\text{'}$Hi$\text{'},$ 'Bye'$)->$ 'HiByeByeHi'

make$\_$abba$(\text{'}$Yo$\text{'},$ 'Alice'$)->$ 'YoAliceAliceYo'

make$\_$abba$(\text{'}$What$\text{'},\text{'}$Up$\text{'})->$ 'WhatUpUpWh