input: Write a python function to remove vowels from a given string.
  assert remove_vowels("Hello World") == "Hll Wrld"
  assert remove_vowels("Python Programming") == "Pythn Prgrmmng"
  assert remove_vowels("Data Science") == "Dt Scnc"
output: def remove_vowels(s: str) -> str:
      vowels = "aeiouAEIOU"
      return ''.join(char for char in s if char not in vowels)