Action methods in action!
Pure parse rule:
rule statement_control {
    | <if_statement>      {*}     #= if
    | <while_statement>   {*}     #= while
    | <for_statement>     {*}     #= for
    | ...
}
rule while_statement {
    'while' <EXPR> <pblock> {*}
}
Add {*} markers to denote places to invoke actions