Take a string which is an option,
check if the string is among a given set of options,
then stop the program if option is wrong,
or return the right and complete option.
Usage
check_foption(opt, all)
Arguments
opt
a string, that is a possible otion.
all
a vector of strings, that iS a set of possible options.
Value
Stop the program, or return a string which is a right option.