Comment by ndr

Found out

> Nested function definitions with @tacopy decorators are not supported. Functions decorated with @tacopy must be defined at module level. This constraint exists because inspect.getsource() on nested functions returns the source of the entire enclosing function, making it impossible to reliably extract and transform just the nested function's code. The decorator detects nested functions by checking for '<locals>' in the function's __qualname__ attribute and raises a clear error message instructing users to extract the function to module level.

https://github.com/raaidrt/tacopy/blob/8f5db70da2b7bbfafc41b...