Ask the user for a custom message and then print it out with a border of $\text{'}$@$\text{'}$ surrounding it$.$

Use the input function to ask the user for a message and store it in the variable a$.$ Use string multiplication and the length of a to assign the top and bottom border of the box to the variable top $($be sure to add $4$ to the length to account for the left and right border$).$ Print top, the message with a $\text{'}$@$\text{'}$ and a $\text{'}\text{'}$ on both sides, and the top again. When you have you program working, test it with the message 'big message!$\text{'}.$