* must have an a list (labels (label index)*)

labels ::= "labels" (label instrNo)*

stmnt ::= for | if | innerstatement

innerStatement ::= PRINT (item ((COMMA | SEMIC) item)*)?
                | NEXT
                | GOTO INT
                | GOSUB INT
                | INPUT VAR| INPUT STRING VAR
                | LET VAR expr
                | RETURN

for ::= FOR var expr TO expr
if ::=  IF expr ?comp expr THEN innerStatement
expr ::= a postfix arithmetic statement
FOR ::= 'FOR'
IF ::= 'IF'
THEN ::= 'THEN'
TO ::= 'TO'
LET ::= 'LET'
RETURN ::= 'RETURN'
INT ::= an integer
NEXT ::= 'NEXT'
INPUT ::= 'INPUT'
STRING ::= QUOTE PRINTABLECHARS QUOTE
QUOTE ::= '"'
PRINTABLECHARS ::= 
VAR ::= a single character (upper case)