syntax_data: {"ast_node_type":"other","tokens":[{"end":38,"kind":"keyword","start":0,"text":"write!(self,"}]}
source_snippet:                 write!(self, " {{ ")?;
context_before:                 self.pretty_print_opaque_impl_type(def_id, args)?;
context_after:                 self.print_def_path(fn_def_id, fn_args)?;