syntax_data: {"ast_node_type":"other","tokens":[{"end":93,"kind":"keyword","start":0,"text":"///"}]}
source_snippet:     /// between creation of an expansion ID and obtaining its data (e.g. macros are collected
context_before:     /// Each expansion should have an associated expansion data, but sometimes there's a delay
context_after:     /// first and then resolved later), so we use an `Option` here.