usage of "ARGV.first" : and fellow coders, 

I was trying the following code, it's not printing as expected; 

    user = ARGV.first # supposed to ask for user name
    prompt = '> '
    
    puts "Hi, #{user}. How do you like this?"
, however, it only prints:

    Hi, . Do you like me?
    => nil
I tried atom and run it from terminal, I tried repl.it; I even tried c9. Same result. Can someone give me a hint on this please?