asserts generate exceptions conditionally depending on the provided condition. So they affect the control flow similarly to the raise statements. This is why I wanted to have an easy to catch graphics for them and this is why they have a red arrow icon. In order to highlight the fact that the exception is conditional I put the arrow icon into a diamond shape separate element as shown on the example.

Obviously the comments must not be forgotten. The second example shows how the diagram will look like if an assert has both leading and side comments as well as occupies more than one line.