Colorado Gov. John Hickenlooper shows off his socks--one with Democratic presidential candidate Bernie Sanders and the other with Republican candidate Donald Trump – before entering his former brewpub for a book signing event to mark the release of his autobiography Thursday, May 26, 2016, in Denver. Hickenlooper, who is term-limited, is doing book talk rounds this week, reviving speculation that he is positioning himself to join Hillary Clinton's presidential campaign ticket. (Photo by David Zalubowski/AP Photo)

Secondary school graduates play in a fountain as they celebrate the last day of school, traditionally called the “last bell” in central Kiev, Ukraine on May 31, 2019. (Photo by Valentyn Ogirenko/Reuters)

Pupils wearing face masks wait for the opening of their primary school on the first day of the new school year, in Ouagadougou, on October 1, 2020. (Photo by Olympia de Maismont/AFP Photo)

Students walk to school on the first day of their new school year in Giza, south of Cairo, Egypt September 25, 2016. (Photo by Mohamed Abd El Ghany/Reuters)

Secondary school graduates play in a fountain as they celebrate the last day of school, traditionally called the “last bell” in central Kiev, Ukraine on May 31, 2019. (Photo by Valentyn Ogirenko/Reuters)

Students from the private school Gabriel stand in line as they prepare to start their school day in Port-au-Prince, Haiti, Tuesday, January 9, 2024. (Photo by Odelyn Joseph/AP Photo)

Undated David Yarrow handout photo of a gorilla as the self-taught wildlife photographer promotes his book, Encounter. (Photo by David Yarrow/Clearview/PA Wire)