syntax_data: {"ast_node_type":"other","tokens":[{"end":70,"kind":"keyword","start":0,"text":"///"}]}
source_snippet:     /// context with variance `a`, and we encounter a type argument in
context_before:     /// variance of a type with the following meaning. If we are in a
context_after:     /// a position with variance `b`, then `a.xform(b)` is the new