Former Maryland Gov. Martin O'Malley, Sen. Bernie Sanders, I-Vt. and Hillary Clinton at the NBC News-YouTube Democratic presidential debate at the Gaillard Center on Sunday in Charleston, S.C. Stephen B. Morton/AP hide caption

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Iranian President Hassan Rouhani presents the draft budget for the next Iranian fiscal year to the chairman of the Iranian Parliament Ali Larijani at the Iranian parliament in Tehran on Jan. 17, 2016. Anadolu Agency/Getty Images hide caption

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President Obama said he regrets that the rancor between the parties has grown during his watch. "I guarantee I'll keep trying to be better so long as I hold this office," he said. Susan Walsh/AP hide caption

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President Obama looks over a vehicle on the assembly line with autoworker Jeffrey Cook, during his tour of the Ford Motor Co. Chicago Assembly Plant in 2010. Pablo Martinez Monsivais/AP hide caption

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Linguist Geoff Nunberg notes that while workers in today's "gig economy" may have more freedom than they had in years past, they also have less security. Hong Li/Getty Images hide caption

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A sign promotes a real estate project last month in Kunming, China. Construction of residential and commercial properties has outpaced demand in China, a factor that some analysts cite in forecasting another global economic downturn. Zhang Peng/LightRocket via Getty Images hide caption

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Prices, as seen at a gas station in Woodbridge, Va., on Tuesday, are 21 cents a gallon cheaper than this time last year. The drop violates the historic rule that tension such as that currently between key producers Saudi Arabia and Iran causes the cost of a barrel of oil to rise. Saul Loeb/AFP/Getty Images hide caption

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Iranian security forces stand guard as protesters demonstrate outside the Saudi Arabian Embassy in Tehran. The crowd was decrying the execution of Nimr al-Nimr, a prominent Saudi Shiite cleric, by Saudi authorities — an execution that has heightened sectarian tensions in the region. Anadolu Agency/Getty Images hide caption

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