def list_remove(list_a, list_b):
    """
    Fine all elements of a list A that does not exist in list B.
    
    Args
      list_a: list A
      list_b: list B
    Returns
      list_c: result  
    """
    list_c = []
    for item in list_a:
        if item not in list_b:
            list_c.append(item)
    return list_c