input: Write a function that takes in a string and returns a new string with all vowels removed. The function should handle both uppercase and lowercase vowels.
  assert no_vowels("Hello World")=="Hll Wrld"
  assert no_vowels("Python Programming")=="Pythn Prgrmmng"
  assert no_vowels("")==""
  assert no_vowels("AEIOUaeiou")==""
  assert no_vowels("bcdfghjklmnpqrstvwxyzBCDFGHJKLMNPQRSTVWXYZ")=="bcdfghjklmnpqrstvwxyzBCDFGHJKLMNPQRSTVWXYZ"
output: def no_vowels(s):
      vowels = "AEIOUaeiou"
      return ''.join([char for char in s if char not in vowels])