new_contents: '''
  Assume s is a string of lower case characters.
  
  Write a program that counts up the number of vowels contained in the string s. 
  Valid vowels are: 'a', 'e', 'i', 'o', and 'u'. For example, if s = 'azcbobobegghakl', 
  your program should print:
  
  Number of vowels: 5
  '''
  
  vow = 0
  
  for i in s:
      if i in 'aeiou':
          vow += 1
  print 'Number of vowels: ', vow
  
subject: Create problem1.py