pub fn rewrite_extern_crate(context: &RewriteContext, item: &ast::Item) -> Option<String> {
assert!(is_extern_crate(item));
let new_str = context.snippet(item.span);
pub fn rewrite_extern_crate(context: &RewriteContext, item: &ast::Item) -> Option<String> {
assert!(is_extern_crate(item));
let new_str = context.snippet(item.span);