### assert: boolean expression
    unless (boolean expression) { die the boolean expression is false with a dump of the elements in the expression }
    ### verify: boolean expression
    unless (boolean expression) { warn the boolean expression is false with a dump of the elements in the expression }
    ### dump: list
    if (DEBUG) { warn with a dump of the elements in the list }
    ### evaluate: expression
    if (DEBUG) { warn value of expression = expression }
    ### "string"
    if (DEBUG) { warn "string" }
    ### <Perl code>
    <Perl code>