fix if_stmt grammar
previous `if_stmt` grammar couldn't capture `else` statement properly as it wasn't nested properly into the `if_stmt`
block. This change would nest all `if` and `else` in one `if_stmt`.
@@ -9,11 +9,11 @@ stmt -> (if_else
| annotation
) attribs?;
-if_else -> if_stmt else_stmt*;
+if_else -> if_stmt (\n+ %level else_stmt)*;
if_stmt -> "if" PREDICATE ":" %!Indented(stmt);
-else_stmt -> "else" PREDICATE? ":" %!Indented(stmt);
+else_stmt -> "else" ("if"? PREDICATE)? ":" %!Indented(stmt);
for_stmt -> for_type=("alt" | "until" | "for each" | "for" | "loop" | "while") PREDICATE ":" %!Indented(stmt);
