program : line+ Eof
line    : indent* expr Eol|Eof

        | indent* Var id Eol|Eof
        | indent* Var id Ass expr Eol|Eof
        | indent* id Ass expr Eol|Eof
        | indent* id (Pls|Sub|Mul|Div)Ass expr Eol|Eof

        | indent* If expr Eol block(+1) (Else (if expr)? Eol block(+1))+

        | indent* Loop Eol block(+1, Break, Continue)
        | indent* While expr Eol block(+1, Break, Continue)
        | indent* For id (Comma id)? In list Eol block(+1, Break, Continue)

        | indent* Fun id OpnBrace (id Comma?)* ClsBrace Eol block(+1, Return)

        | indent* Seq id Square (Ass list)? Eol|Eof
        | indent* id OpnSqr expr ClsSqr Ass expr Eol|Eof

        | indent* Eol|Eof
+
break   : indent* Break Eol
continue: indent* Continue Eol
return  : indent* Return expr? Eol

list    : listref
        | expr (Comma expr)*

listref : id Square
        | OpnBrace list ClsBrace

expr    : ored
ored    : anded (Or anded)*
anded   : inversed (And inversed)*
inversed: not compared
compared: added (Is Not? added)?
        | added (>|<|>=|<= added)?
added   : timesed (Pls|Sub timesed)*
multied : signed (Mul|Mod|Div signed)*
signed  : -?dotcall
dotcall : num (Dot id OpnBrace (expr Comma?)* ClsBrace)*
num     : digit
        | id
        | id OpnSqr expr ClsSqr ^Ass?
        | id OpnBrace (expr|lazylist Comma?)* ClsBrace
        | OpnBrace expr ClsBrace
        | lazylist Dot OpnBrace (expr|lazylist Comma?)* ClsBrace
id      : non-digit(alphanumeric,_)*

indent  : '    '
block(n): (indent*n line)+