"U.S. President Barack Obama demonstrates ""the Soccket Ball,"" which uses kinetic energy to provide power to charge a cell phone or power a light, during an event at the Ubungo power plant to promote energy innovation on Tuesday, July 2, 2013, in Dar Es Salaam, Tanzania. The president is traveling in Tanzania on the final leg of his three-country tour in Africa. (AP Photo/Evan Vucci)"
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