input: Write a Python function to extract integers from a provided list of various Python elements.
  
  assert extract_integers([]) == []
  
  assert extract_integers([4, {}, [], 23.2, 9, 'adasd']) == [4, 9]
  
  assert extract_integers([3, 'c', 3, 3, 'a', 'b']) == [3, 3, 3]
output: def extract_integers(elements):
      return [x for x in elements if isinstance(x, int)]