pub fn signals_type(&self) -> bool {
        use self::Token::*;
        match *self {
            TI8 | TI16 | TI32 | TI64 | TU8 | TU16 | TU32 | TU64 | TF32 | TF64 | TBool | TVec
            | TSimd | TAppender | TMerger | TDict | TDictMerger | TGroupMerger | TVecMerger
            | TOpenBrace | TQuestion => true,
            _ => false,
        }
    }
Returns true if the token signifies the beginning of a type parse.

This does not include aliases, which can be any symbol name.
weld/src/syntax/tokenizer.rs