Raeez Safar sits in a grassy courtyard, his eyes closed as he lifts his hands to his face. The sleeves of his white top fall past his wrists, revealing a small, neat gang tattoo of the number “26”. Safar is one of more than 250 South African prisoners who regularly do yoga. He says it helps him cope with incarceration at Pollsmoor, one of the country’s most notorious prisons. “Yoga makes me feel positive about…