token keyword {
         | yield      | abstract   | and        | array        | as
         | break      | callable   | case       | catch        | class
         | clone      | const      | continue   | declare      | default
         | die        | do         | echo       | else         | elseif
         | empty      | enddeclare | endfor     | endforeach   | endif
         | endswitch  | endwhile   | eval       | exit         | extends
         | final      | for        | foreach    | function     | global
         | goto       | if         | implements | include      | include_once
         | instanceof | insteadof  | interface  | isset        | list
         | namespace  | new  | or  | print      | private
         | protected  | public     | require    | require_once | return
         | static     | switch     | throw      | trait        | try
         | unset      | use | var  | while      | xor
    }