could not find function "layer_dense"

This error message typically appears when a Python script is trying to use the Keras `layer_dense` function, but it cannot be found. This could be due to a few different reasons:

1. The Keras library is not installed: Make sure that you have installed Keras by running `pip install keras`. If you are using TensorFlow 2.0 or later, Keras should already be included.

2. The `layer_dense` function has been deprecated: In more recent versions of Keras, the `layer_dense` function has been replaced with `Dense`. Try updating your code to use `Dense` instead.

3. You have a typo in your code: Double-check your code to make sure that you have spelled `layer_dense` correctly and that it is being called correctly.

If none of these solutions work, please provide more context and code so that I can better understand the issue.