##### Use declarations
~~~~~~~~ {.ebnf .gram}
-use_decl : "pub"? "use" ident [ '=' path
+use_decl : "pub" ? "use" ident [ '=' path
| "::" path_glob ] ;
path_glob : ident [ "::" path_glob ] ?
### Vector expressions
~~~~~~~~{.ebnf .gram}
-vec_expr : '[' "mut"? vec_elems? ']'
+vec_expr : '[' "mut" ? vec_elems? ']'
vec_elems : [expr [',' expr]*] | [expr ',' ".." expr]
~~~~~~~~