= Python Challenge -- Level 3 -- Solution =

==== Code ====

{{{
#!d
import tango.io.Stdout;
import tango.text.Regex;

void main () {
        char[] text = "";

        Regex pattern = Regex("[^A-Z]([A-Z]{3}([a-z])[A-Z]{3})[^A-Z]");

        foreach (Regex match; pattern.search(text))
                Stdout.print(match.match(2));
        Stdout.flush();
}
}}}

==== Explanation ====

{{{
#!d
        char[] text = "";
}}}

The source text from the challenge page should be put between the quotes.

{{{
#!d
        Regex pattern = Regex("[^A-Z]([A-Z]{3}([a-z])[A-Z]{3})[^A-Z]");
}}}

Create a new regular expression that does the following things:
 * {{{ [^A-Z] }}}
   * The character must not be an uppercase letter.
 * {{{ [A-Z]{3} }}}
   * There must be three uppercase letters in a row.
 * {{{ [a-z] }}}
   * The character must be a lowercase letter.
 * {{{ [A-Z]{3} }}}
   * There must be three uppercase letters in a row.
 * {{{ [^A-Z] }}}
   * The character must not be an uppercase letter.

{{{
#!d
        foreach (Regex match; pattern.search(text))
}}}

For every match of the pattern, execute the following code.

{{{
#!d
                Stdout.print(match.match(2));
        Stdout.flush();
}}}

Print the second tagged statement to the screen.  The tagged statement are delimited by the parenthesis.  Upon completion, the data is flushed.