anchor.diff:          };
   
           betweenDesc = lowest: highest:
  -          "${toString lowest} and ${toString highest} (both inclusive).";
  +          "${toString lowest} and ${toString highest} (both inclusive)";
           between = lowest: highest: assert lowest <= highest;
             addCheck int (x: x >= lowest && x <= highest) // {
               name = "intBetween";
  -            description = "Integer between ${betweenDesc lowest highest}";
  +            description = "Integer between ${betweenDesc lowest highest}.";
             };
           ign = lowest: highest: name: docStart:
             between lowest highest // {
               inherit name;
  -            description = docStart + " Between ${betweenDesc lowest highest}";
  +            description = docStart + " Between ${betweenDesc lowest highest}.";
             };
           unsign = bit: range: ign 0 (range - 1)
             "unsignedInt${toString bit}" "${toString bit} bit unsigned integer.";
  
positive.code:           "signedInt${toString bit}" "${toString bit} bit signed integer.";
  
        in rec {
          /* an int with a fixed range
          *
          * Example:
          *   (ints.between 0 100).check (-1)
  
negative.code:         signed32 = sign 32 4294967296;
  
        };
  
      /* A network port number */
      port = ints.unsigned16;
  
      str = mkOptionType {
        name = "str";
  