Carefully observe the following Python script and determine the output $($or error$).$ def example$($a$)$:

$a=a+\text{'}2\text{'}$

$a=a*2$

return a

$x=$ example$("$roger$")$

print $(x)$

$$ indentation error

cannot perform mathematical operations on strings

roger $2$

roger $2$ roger $2$