class Gem::Resolv::IPv4

def self.create(arg) 

def self.create(arg)
  case arg
  when IPv4
    return arg
  when Regex
    if (0..255) === (a = $1.to_i) &&
       (0..255) === (b = $2.to_i) &&
       (0..255) === (c = $3.to_i) &&
       (0..255) === (d = $4.to_i)
      return self.new([a, b, c, d].pack("CCCC"))
    else
      raise ArgumentError.new("IPv4 address with invalid value: " + arg)
    end
  else
    raise ArgumentError.new("cannot interpret as IPv4 address: #{arg.inspect}")
  end
end