在Ruby中打印嵌套哈希中的所有键值？

def print_hash(hash)
  hash.each do |key, value|
    if value.is_a?(Hash)
      puts "#{key}:"
      print_hash(value)
    else
      puts "#{key}: #{value}"
    end
  end
end

# 示例嵌套哈希
nested_hash = {
  key1: "value1",
  key2: {
    nested_key1: "nested_value1",
    nested_key2: {
      nested_nested_key1: "nested_nested_value1"
    }
  },
  key3: "value3"
}

print_hash(nested_hash)

key1: value1
key2:
nested_key1: nested_value1
nested_key2:
nested_nested_key1: nested_nested_value1
key3: value3