I'm Michel Martin and this is TELL ME MORE from NPR News. Summer is the time when many people decide to take that trip they've been putting off to visit distant relatives, introduce the kids and maybe even bring home some business. Presidents are no different. President Obama and his family are in Africa now. It'll be the longest visit to Africa of his presidency and has been much anticipated on the continent, after his barely 24-hour visit to just one country, Ghana, in his first term.