## Attributes
```{.ebnf .gram}
-attribute : "#!" ? '[' meta_item ']' ;
+attribute : '#' '!' ? '[' meta_item ']' ;
meta_item : ident [ '=' literal
| '(' meta_seq ')' ] ? ;
meta_seq : meta_item [ ',' meta_seq ] ? ;
### While loops
```{.ebnf .gram}
-while_expr : "while" no_struct_literal_expr '{' block '}' ;
+while_expr : [ lifetime ':' ] "while" no_struct_literal_expr '{' block '}' ;
```
A `while` loop begins by evaluating the boolean loop conditional expression.
### For expressions
```{.ebnf .gram}
-for_expr : "for" pat "in" no_struct_literal_expr '{' block '}' ;
+for_expr : [ lifetime ':' ] "for" pat "in" no_struct_literal_expr '{' block '}' ;
```
A `for` expression is a syntactic construct for looping over elements provided