print_r for Ruby

print_r is a function that PHP developers like to use to display the contents of an object. Here's a version I wrote for Ruby:

def print_r(hash, level=0)
  result = "  "*level + "{\n"
  hash.keys.each do |key|
    result += "  "*(level+1) + "#{key} => "
    if hash[key].instance_of? Hash
      result += "\n" + print_r(hash[key], level+2)
    else 
      result += "#{hash[key]}\n"
    end
  end
  result += "  "*level + "}\n"
end

It pretty-prints the contents of a nested map; for example, print_r({"A"=>1, "B"=>{"a"=>"@", "s"=>"$"}, "C"=>3}) displays the following:

{
  A => 1
  B =>
    {
      a => @
      s => $
    }
  C => 3
}