Wait, so the pipeline step only runs if the pre execute callback returns True? It'll stop if it doesn't run?

Only if you have a Callback function, and that callback function returns False, then it will skip it (otherwise it will process it)

Another question, in the parents sequence in pipe.add_step, we have to pass in the name of the step right?

Correct, the step name is a unique identifier for the pipeline

how would I access the artifact of a previous step within the pre execute callback? Can you share an example?

Basically you can do:
def pre_execute_callback_example(a_pipeline, a_node, current_param_override): # type (PipelineController, PipelineController.Node, dict) -> bool nodes = a_pipeline.get_pipeline_dag() parent_task_id = nodes[a_node.parents[0]].executed Task.get_task(parent_task_id).artifacts[...]

Is the only possible way to get a specific node

See the following (it is a dictionary where the key is the step/node unique name)
pipeline.get_pipeline_dag()