#obstacle  an obstruction that stands in the way (and must be removed or surmounted or circumvented)
  supertype:  #obstructor__obstruction__obstructer__impediment__impedimenta  any structure that makes progress difficult
  subtype:  #hazard  an obstacle on a golf course
     subtype:  #sand_trap__bunker__trap  a hazard on a golf course
     subtype:  #water_hazard__waterhazard  hazard provided by ponds of water that the golfer must avoid
  subtype:  #stumbling_block__stumblingblock  any obstacle or impediment
  subtype:  #water_jump__waterjump  a pool or stream in a steeplechase or similar contest

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