Write a function before$\_$a$($word$)$ that takes in a string representing a single lowercase English word, and returns the same word but with all letters that come before the first $\text{'}$a$\text{'}$ moved to the end of the string $($NOT including the $\text{'}$a$\text{'}$ itself$).$ Only the location of the first $\text{'}$a$\text{'}$ matters.$$ You can assume there will be at least one $\text{'}$a$\text{'}.$

Submit your code to Gradescope in a file called ex$8-2.$py$.$

Examples:

if $\_\_$name$\_\_==\text{'}\_\_$main$\_\_\text{'}$:

$$print$($before$\_$a$(\text{'}$trains$\text{'}))$ #ainstr

$$print$($before$\_$a$(\text{'}$attractor$\text{'}))$ #attractor

$$print$($before$\_$a$(\text{'}$chronophobia$\text{'}))$ #achronophobi