Consider the PDA P from Exercise $6\mathrm{.}1\mathrm{.}1.$ a$)$ Convert P to another PDA P$1$ that accepts by empty stack the same language that P accepts by final state; i$.$e$.,$ N$($P$1)=$ L$($P$).$ b$)$ Find a PDA $?$such that L$($P$2)=$ N$($P$)$; i$.$e$.,?$accepts by final state what P accepts by empty stack.