A Ruby Quirk

# $ denotes global variables in Ruby.

def function()
$number += 1;
$number += 2;
$number += 3;
return 4;
end

$number = 0;
$number += function();

Problem: What is in $number at the end of this code?

Answer (select to see): 4. the command at the end unfolds to '$number = $number + function()', then '$number = 0 + function()' before it executes function().