With no explanation, label text_A→text_B with either "NOT ENOUGH INFO", "REFUTES" or "SUPPORTS".
text_A: Justin Vernon was the vocalist of West at Glastonbury Festival in 2015 .
text_B: Vernon has on several occasions served as backing vocalist for West at his live performances , notably at the Coachella Valley Music and Arts Festival in 2011 and Glastonbury Festival in 2015 .
SUPPORTS.