Re/code: Medium, the publishing platform hatched by Twitter co-founder Ev Williams, has raised $57 million in a round led by Andreessen Horowitz. It’s the three-year-old company’s second funding round, and people familiar with Medium say it places a $400 million pre-money valuation on the startup. In the old days, that might have seemed like a lofty number for a company that has yet to generate much revenue; today it seems like a modest sum.