NameError: name 'print_string' is not defined

[buran]

check line 41, do you really want the return statement at that place in the function and with that indentation? what will happen if the else block is executed? print_string has local scope - it exists only inside the function and is not accessible outside it. Do you want lines 43-48 inside the function. If it should be outside - ship_method (local scope inside the function) will not be accessible and will cause NameError
Note that there is a LOT of redundant code...