syntax_data: {"ast_node_type":"other","tokens":[{"end":33,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:     // will branch to `drops[n]`.
context_before:     // block begins as the successor of `drops[n]` and then becomes `drops[n]` so that `drops[n-1]`
context_after:     let mut block = block;