It pains me to monkey-patch Ruby builtins. Also, it's brittle since right_support needs to be compatible with Ruby 1.8.7 - 2.0

Could we subclass IPAddr instead, something like this?

class IPNet < ::IPAddr
  # defines cidr_block(), and perhaps size() to return the number of hosts in the net (replacing is_host?)
  # overrides to_s so it returns valid CIDR notation
end