case state of
...
f1: begin {identifier}
if symbol in ['a'..'z', '0'..'9'] then
str := str + symbol;
else
begin
ungetchar(symbol); {return symbol}
if is_keyword(str) then {keyword}
TOKEN :=
get_keyword(str);
else
TOKEN :=
IDENTIFIER;
break;
end;
end; {state f1}