syntax_data: {"ast_node_type":"other","tokens":[{"end":89,"kind":"keyword","start":0,"text":"///"}]}
source_snippet:         /// (e.g. `0` for `*mut T`, `1` for `MyStruct<'CovariantParam, 'InvariantParam>`)
context_before:         /// The index of the generic parameter being used
context_after:         param_index: u32,