President Obama and British Prime Minister David Cameron pose for a picture with Denmark's Prime Minister, Helle Thorning Schmidt, during the memorial service for Nelson Mandela Tuesday in Johannesburg, South Africa. First lady Michelle Obama is on the right. Roberto Schmidt/AFP/Getty Images hide caption

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People gather to leave messages of support for Nelson Mandela outside his hospital in Pretoria, South Africa, earlier this year. Mandela has died at the age of 95. Jeff J Mitchell/Getty Images hide caption

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Amy Tan's latest novel, The Valley of Amazement, will be published on Tuesday. Rick Smolanagainst/Against All Odds Productions hide caption

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Marc Jacobs is among the designers who were named by the Diversity Coalition for not having enough models of color on the runway. Emmanuel Dunand/AFP/Getty Images hide caption

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Mrs. Fannie Lou Hamer of Ruleville, Miss., speaks to the state's Freedom Democratic Party sympathizers outside the Capitol in Washington, D.C., in 1965. William J. Smith/AP hide caption

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