error: #[arael::function] requires one of:
         - Form A: `fn name(x: E, ...) -> E`
         - Form B: `fn name(x: f32, ...) -> f32` (or `f64`, all params and return type uniform)
 --> tests/user_function_errors/bad_signature.rs:6:1
  |
6 | fn bad(x: f32) -> arael_sym::E {
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
