The slide deck is at http://derickrethans.nl/talks/phpexts-zendcon.pdf

Add a new function %helloearth()% that returns %"Hello Earth!"% (slide 23, 42).

Add a new function %hello()% that accepts a string argument, and returns %"Hello «argument»!"% (slide 40/41).

Add the argument info information to the %hello()% function (slide 31).

Add a new function that multiplies a float and an integer and optionally also a boolean (slide 40/41).