syntax_data: {"ast_node_type":"other","tokens":[{"end":90,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:                             // when applying the type to the value being matched, but this
context_before:                             // variance field from the ascription refers to the variance to use
context_after:                             // ascription applies rather to the type of the binding. e.g., in this