seven_boom_without_conditionals

def div_7():

  counter = 1
  while True:
    for i in range(6):
      yield counter
      counter += 1
    yield 'boom'
    counter += 1

def seven_boom_digital(d, sub):

  while True:
    for i in range(10**d):
      yield 'boom'
      next(sub)
    for i in range(9*10**d):
      yield next(sub)

def seven_boom():

  gen = div_7()
  counter = 0
  for n in range(1,7):
    yield next(gen)
  while True:
    gen = seven_boom_digital(counter, gen)
    for n in range(7*10**counter,7*10**(counter+1)):
      yield next(gen)
    counter += 1

gen = seven_boom()
print([next(gen) for n in range(1000)])