Using fetch

gistfile1.txt

> {}.fetch("i-dont-exist")                                             # Raises error for a required key
KeyError: key not found: "i-dont-exist"
from (pry):2:in `fetch'

> {}.fetch("with-a-default", "default-value")                          # Provide a default value as the second argument
=> "default-value"

> {}.fetch("something-special") { puts "do something special here" }   # Yields to a block for custom stuff
do something special here
=> nil