Today is Warren Buffett’s last day as Berkshire CEO. Business leaders tell us what they learned from him

By Luciana Lopez, Elijah Shama, Richard Quest, Erin Burnett, CNN (CNN) — Warren Buffett has worn many hats over the years: The stock-picking Oracle of Omaha. An avuncular, Dairy-Queen-eating, Coke-drinking product pitchman. A living symbol of capitalism and its complexities. But for generations of business leaders, the 95-year-old has also served as something else: a