Guest post from Bob and Kristin Blank: Today we are returning to the U.S. after the best trip of our lives. We have no souvenirs nor amazing photos of beautiful sightseeing spots. Instead, we have hearts and heads full of memories (along with some very dusty tennis shoes!) because Lily and Ellie graciously gave us the opportunity to walk the streets of Bolivia with them for the past week. The street corners, canals and bridges of Santa Cruz are full of kids with hurting hea