The tt(UPPERCASE) macro converts a string or a part of it to upper case. It has
two arguments:

startit()

    it() The string to convert;

    it() A length, indicating how many characters (starting from the beginning
    of the string) should be converted.

endit()

The length indicator can be smaller than one or larger than the length of the
string; in that case, the whole string is convertered.

Example:

verb(\
UPPERCASE(hello world)(1)
UPPERCASE(hello world)(5)
UPPERCASE(hello world)(0))

This code sample expands to:

verb(\
Hello world
HELLO world
HELLO WORLD)
