Create an infinitely nestable hash in Ruby

nestable_hash.rb

# Create the empty hash
nestable_hash = Hash.new { |hash, key| hash[key] = Hash.new(&hash.default_proc) }

# Populate the hash with multiple levels of data
nestable_hash[:level_one][:level_two][:level_three][:level_four] = 'mic check'
nestable_hash[:level_one][:level_two_a][:level_three_a]          = [1, 2, 1, 2]

# The hash structure is now:
# {
#   level_one: {
#     level_two: {
#       level_three: {
#         level_four: 'mic check'
#       }
#     },
#     level_two_a: {
#       level_three_a: [
#         [0] 1,
#         [1] 2,
#         [2] 1,
#         [3] 2
#       ]
#     }
#   }
# }