Conversation so far:
When did Lester Young join the Count Basie Orchestra?
Lester Young was with Count Basie for the first time in 1934.
How long did Lester Young stay a member of the Count Basie Orchestra?
Lester Young was with Count Basie for the first time in 1934, back in 1936, leaving in 1940, rejoining in 1943, and a reunion at the 1957 Newport Jazz Festival.
When did Lester Young leave the Count Basie Orchestra band?
Lester Young was with Count Basie for the first time in 1934 but left to replace Coleman Hawkins in Fletcher Henderson's orchestra.

Question: What instrument did he play?
Self-contained rewrite: What instrument did Lester Young play?