The atoi$()$ function takes a string $($which represents an integer$)$ as an argument and returns its value.

Consider the following two recursive implementations atoiR$1()$ and atoiR$2().$

def atoiR$1($string$,$ num$)$:

if $($len$($string$)==0)$:

return $0$

if string$)==1$ :

return int $($string$)$ num $**10$

num num $**10$

return atoiR$1($string$[1$:$],$ num$)$

def atoiR$2($string$)$:

if $($Len$($string$)==0)$:

return $0$

if len$(string)==1$ :

return int$($string$)$

return atoiR$2($string $[0$:$-1]$

Which of the following is TRUE?

Both atoiR$1$ and atoiR$2$ are tail recursive

atoiR$2$ is tail recursive

Neither atoiR$1$ and atoiR$2$ are tail recursive

atoiR$1$ is tail recursive