The tree holds the token y.
Used by instDecidablePredRoseTreeVertexTokenHolds, holds_leaf, holds_pair, holds_node_of_mem, exists_mem_of_holds_map, holds_of_mem_subtrees, holds_congr, TokenCCommands, tokenCCommands_pair_iff, TokenCCommands.holds, coe_mem_terms_iff, holds_iff_mem_yield, exists_holds
Used in Syntax/Minimalist/Copy/Reading