Optional Parameter ?

Is it possible to have a function that looks something like function print_this( $value1, $value2, $maybe3) { do whatever; } that would expect $value1, $value2 BUT would not care if $maybe3 came in or not ? and not give an error message that there is a missing paramter ? I know I can do a condition within the function, but just want to see if there is a more technical approach as in from php to ignore that optional per say variable. I did look in my PHP book by wrox, but no luck. Thanks !!!