Yes, when you get a syntax error at the beginning of a line, it usually means you left out something on the previous line. In this case, you are building a list of layers. For a list in python, the items need to be separated by commas, right?
Note that they don’t really give you a lot of help here learning how to use the Keras Sequential and Functional APIs. In the next section of this assignment, you’ll be using the Functional API and you don’t want commas between the layers. Here’s a thread that’s a good way to get a more detailed introduction to these new APIs.