input: Write a python function to remove vowels from a given string.
  assert removeVowels('hello world') == 'hll wrld'
  assert removeVowels('Python Programming') == 'Pythn Prgrmmng'
  assert removeVowels('aeiouAEIOU') == ''
  assert removeVowels('ABCDEFG') == 'BCDFG'
output: def removeVowels(s):
      vowels = "aeiouAEIOU"
      return ''.join(char for char in s if char not in vowels)