syntax_data: {"ast_node_type":"other","tokens":[{"end":64,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:         //   +-+----------------------------------+------------+
context_before:         //   |2| _8 = &mut _1                     | +_8        |
context_after:         // E |T| _4 = const Foo::twiddle(move _2) | -_2        |