Hi @MilesCranmer, poking through the weeds a bit here but I noticed you've added the following check in v1.10.4 and v2.5.0 when converting expressions to symbolic forms:

Shouldn't the package still allow for custom operators that are formed from combinations of the SUPPORTED_OPS? E.g., if we had a unary operator pow2(x) = x*x. This used to work fine for me in v1.10.3, but now in v1.10.4 I get the intended error from the above if statement.

Thanks in advance!