Assertion: trombone's valve | /r/CapableOf | force the player
Facets:
value: to use both hands
type: PURPOSE
Source sentences:
text: One of the best known early types was the valide trombone invented by jazz trombonist and reedist Brad Gowans, which featured a slide on the inside on the valves which did not lock, forcing the player to actively use both hands.