input: Write a python function to remove vowels from a given sentence.
  assert removeVowels("This is a test sentence.") == "Ths s  tst sntnc."
  assert removeVowels("Hello World") == "Hll Wrld"
  assert removeVowels("aeiou") == ""
output: def removeVowels(sentence):
      vowels = "aeiouAEIOU"
      return ''.join([char for char in sentence if char not in vowels])