Complex Flows: Subflows & Mapping

Day 66 of 100 Days of MLOps. So far every pipeline has been a straight line. Real ones branch and fan out. Today you learn two Prefect tools that turn a linear flow into a real workflow: subflows (call one flow inside another, for modular, reusable pipelines) and mapping (.map() runs one task over many inputs concurrently — a whole hyperparameter sweep in parallel). You'll build a flow that prepares data in a subflow, then fans a training task across four hyperparameters at once. Runs 100% locally on any OS.