Ruby Hash `deep_compact` and `deep_compact!`

deep_compact.rb

class Hash
  # Returns a new hash with the nil values/key pairs removed recursively.
  #
  #   hash = { a: true, b: { c: [1, 2, 3], d: { e: nil, f: 4 } }, g: nil }
  #
  #   hash.deep_compact # => { a: true, b: { c: [1, 2, 3], d: { f: 4 } } }
  def deep_compact
    dup.deep_compact!
  end

  # Same as +deep_compact+, but modifies +self+.
  def deep_compact!
    # `compact!` Returns nil if no changes were made, otherwise returns the hash.
    # When nil, old hash is rescued.
    hash = self
    (compact! || hash).each do |key, value|
      self[key] = value.is_a?(Hash) ? value.deep_compact : value
    end
    self
  end
end