input: Write a function to count the total number of vowels in a given string. The function should return the count of vowels (a, e, i, o, u) in the string, considering both uppercase and lowercase characters.
  
  def count_vowels(string): 
      vowels = "aeiou"
      count = 0
      for s in string:
          if s.lower() in vowels:
              count += 1
      return count
  
  assert count_vowels("Hello World")==3
  assert count_vowels("Python Programming")==4
  assert count_vowels("Abracadabra")==5
  assert count_vowels("AEIOU")==5
  assert count_vowels("Thx")==0
output: def count_vowels(string): 
      vowels = "aeiou"
      count = 0
      for s in string:
          if s.lower() in vowels:
              count += 1
      return count