\r
exception ParsingError of string;;\r
\r
-let isAlphaNum c = let n = Char.code c in 48 <= n && n <= 122 ;;\r
+let isAlphaNum c = let n = Char.code c in\r
+ (48 <= n && n <= 90) || (95 <= n && n <= 122) ;;\r
let isSpace c = c = ' ' || c = '\n' || c = '\t' ;;\r
\r
let rec index_of x =\r