syntax_data: {"ast_node_type":"function","tokens":[{"end":78,"kind":"keyword","start":0,"text":"fn"}]}
source_snippet:     fn is_transmutable(src: Self, dst: Self, assume: Assume) -> Answer<!, !> {
context_before: impl Representation for Tree {
context_after:         crate::maybe_transmutable::MaybeTransmutableQuery::new(