digdig.rb

class Array
  def keys
    0...size
  end
end

def find(it, key, &blk)
  it.keys.each do |k|
    v = it[k]
    k == key ? yield(v) :  find(v, key, &blk)
  end
rescue
  # nop
end

e = ENV.to_hash
e['more'] = ENV.to_hash
e['x'] = [1,2,3, ENV.to_hash]
find(e, 'SHELL') {|x| p x}