def calc_seasonality(freq):
  if freq == 'Y':
    return 10
  elif freq == 'Q':
    return 4
  elif freq == 'M':
    return 12
  elif freq == 'W':
    return 4
  elif freq == 'D':
    return 7
  else:
    return "You didn't choose the correct frequency. Use: Y, Q, M, W and D"