syntax_data: {"ast_node_type":"other","tokens":[{"end":59,"kind":"keyword","start":0,"text":"unsound_mir_opts:"}]}
source_snippet:     unsound_mir_opts: bool = (false, parse_bool, [TRACKED],
context_before:         `mir` (the MIR), or `mir-cfg` (graphviz formatted MIR)"),
context_after:         "enable unsound and buggy MIR optimizations (default: no)"),