docs: def validate_setup(transactions):
      """ First two transactions must set rate & days. """
      if not transactions:
          return True
      try:
          first, second = transactions[:2]
      except ValueError:
          print('Error: vacationrc file must have both initial days and rates entries')
          return False
  
      parts1, parts2 = first.split(), second.split()
  
      if parts1[0] != parts2[0]:
          print('Error: First two entries in vacationrc must have the same date')
          return False  # Dates must match
  
      if 'rate' not in (parts1[1], parts2[1]) or 'days' not in (parts1[1], parts2[1]):
          print('Error: First two entries in vacationrc must set days and rate')
          return False
  
      return True