buddydvd

    [\w\.-_]

    [\w\.\-_]

  # show only items in both a and b
  comm -1 -2 <(sort -u a_list) <(sort -u b_list)

  # show only items unique to a
  comm -2 -3 <(sort -u a_list) <(sort -u b_list)

  # show only items unique to b
  comm -1 -3 <(sort -u a_list) <(sort -u b_list)

    ["pAsSwOrD", "PaSsWoRd", "PAsSwOrD"].map(function canonicalize(pwd) {
        function invert(str) {
            return (str == str.toUpperCase()
                    ? str.toLowerCase()
                    : str.toUpperCase());
        }
        var head = pwd.substring(0, 1).toLowerCase();
        var tail = pwd.substring(1);
        var vers = [head + tail,
                    head + tail.split("").map(invert).join("")];
        return vers.sort()[0];
    });

    ["pAsSwOrD", "pAsSwOrD", "pAsSwOrD"]

    14.9.1 What is Cacheable

    By default, a response is cacheable if the requirements of the
    request method, request header fields, and the response status
    indicate that it is cacheable.

    Responses to this method are not cacheable, unless the response
    includes appropriate Cache-Control or Expires header fields. However,
    the 303 (See Other) response can be used to direct the user agent to
    retrieve a cacheable resource.