text: #!/usr/bin/env python3
  """script to count number of vowels in a single string"""
  
  import sys
  import os
  
  def main():
      """main"""
  
  vowels = sys.argv
  
  if len(vowels) < 2:
      script = os.path.basename(vowels[0])
      print('Usage: {} STRING'.format(script))
      sys.exit(1)
  
  vowels = sys.argv[1]
  count = 0
  
  for vowel in vowels:
      if(vowel =='a' or vowel =='e' or vowel =='i' or vowel =='o' or vowel =='u' or vowel =='A' or vowel =='E' or vowel =='I' or vowel =='O' or vowel =='U'):
          count += 1
      
  if count == 0:
      print('There are 0 vowels in "{}."'.format(vowels))
  elif count < 2:
      print('There is 1 vowel in "{}."'.format(vowels))
  else:
      print('There are {} vowels in "{}."'.format(count, vowels))
  
  main()