syntax_data: {"ast_node_type":"other","tokens":[{"end":73,"kind":"keyword","start":0,"text":"///"}]}
source_snippet:     /// various ways you can do this, but a De Bruijn index is one of the
context_before:     /// fn type it is bound by, the inner or the outer one. There are
context_after:     /// more convenient and has some nice properties. The basic idea is to