input: Write a python function to generate a list of 20 random numbers between 0 and 20.
  assert len(generateRandomNumbers()) == 20
  assert all(0 <= num <= 20 for num in generateRandomNumbers())
  assert isinstance(generateRandomNumbers(), list)
output: import random
  
  def generateRandomNumbers():
      return [random.randint(0, 20) for _ in range(20)]