class Flow:
    def flow(self, place):
        r = 

function GI.play!(env::Env, action)
  r = self.observe(action)
  self.last_reward = r
  return

class Flow:
    def flow(self, place):
        r = 

function GI.play!(env::Env, action)
  r = self.observe(action)
  self.last_reward = r
  return
