Remove dead code (private, wasn't called locally)

lib/cidr.ex

@@ -165,32 +165,6 @@ defmodule CIDR do
     { a1, b1, c1, d1, e1, f1, g1, h1 }
   end
 
-  defp is_ipv6({a, b, c, d, e, f, g, h}) do
-    a in 0..65535 and
-    b in 0..65535 and
-    c in 0..65535 and
-    d in 0..65535 and
-    e in 0..65535 and
-    f in 0..65535 and
-    g in 0..65535 and
-    h in 0..65535
-  end
-  defp is_ipv6(_), do: false
-
-  defp is_ipv4({a, b, c, d}) do
-    a in 0..255 and
-    b in 0..255 and
-    c in 0..255 and
-    d in 0..255
-  end
-  defp is_ipv4(_), do: false
-
-  defp mask_by_ip(address) do
-    cond do
-      is_ipv4(address) ->  32
-      is_ipv6(address) -> 128
-    end
-  end
 
   defp int(x) do
     case x |> Integer.parse do