syntax_data: {"ast_node_type":"variable","tokens":[{"end":77,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:                 let rhs = unpack!(block = this.as_local_operand(block, rhs));
context_before:                 // As above, RTL.
context_after:                 let lhs = unpack!(block = this.as_place(block, lhs));