import time

class Writer:
   def __init__(self):
      self.previous = Line(None)

   def write(self, v):
      latest = Line(v)
      chosen = Line.choose(self.previous, latest)
      if chosen.v != self.previous.v:
         print(chosen)
      self.previous = chosen

class Line:
   def __init__(self, v):
      self.t = time.time()
      self.v = v

   def __str__(self):
      return f'@{self.t} | {self.v}'

   def choose(a, b):
      if not a:
         return b
      if not b:
         return a
      latest = max([a,b], key=lambda x:x.t)
      oldest = min([a,b], key=lambda x:x.t)
      if not latest.v and time.time() - oldest.t < 1:
         return oldest
      return latest