better use fetch

use_fetch.rb

{}[:width]                      # => nil
{}[:width] || 40                # => 40
{:width => nil}[:width] || 40   # => 40
{:width => false}[:width] || 40 # => 40
{:width => 29}[:width] || 40    # => 29

{}.fetch(:width)                     # =>
# ~> -:7:in `fetch': key not found (IndexError)
{}.fetch(:width) { 40 }         # => 40
{:width => nil}.fetch(:width) {40} # => nil
{:width => false}.fetch(:width) {40} # => false
{:width => 29}.fetch(:width) {40}    # => 29