syntax_data: {"ast_node_type":"other","tokens":[{"end":58,"kind":"keyword","start":0,"text":"mir_preserve_ub:"}]}
source_snippet:     mir_preserve_ub: bool = (false, parse_bool, [TRACKED],
context_before:         "MIR optimization level (0-4; default: 1 in non optimized builds and 2 in optimized builds)"),
context_after:         "keep place mention statements and reads in trivial SwitchInt terminators, which are interpreted \