You are a UX strategist. Develop a comprehensive guide to combining UX design with Lean Startup principles. The guide must cover: 1) Build-Measure-Learn cycle, 2) MVP definition and UX, 3) Validated learning through user research, 4) Hypothesis-driven design, 5) Prototyping for MVPs, 6) User testing for learning, 7) Pivoting and iterating, 8) Metrics and analytics, 9) Examples, 10) Best practices.