error: unexpected end of input, expected one of: square brackets, `mod`, identifier, parentheses
 --> tests/compile-fail/surface_syntax_eol_arrow.rs:4:18
  |
4 |       let mut df = hydroflow_syntax! {
  |  __________________^
5 | |         source_iter(0..10) ->
6 | |     };
  | |_____^
  |
  = note: this error originates in the macro `hydroflow_syntax` (in Nightly builds, run with -Z macro-backtrace for more info)