pub fn display_kind(kind: &TokenKind) -> &'static strExpand description
the human spelling of a token kind, for error messages: ) not RParen,
end of input for TokenKind::Eof, a category name for the
payload-carrying kinds (an identifier, an integer literal).
this is the one place the mapping lives, so a new token kind is one line
here. the strings are quoted where the token is a literal symbol so a
message reads “expected , or )”, not “expected , or )”.