def inCommon(lst1, lst2):
    """Return elements in common between both lists"""
    if lst1 == None or type(lst1) != list:
        raise ValueError("lst1 must be a list.")    
    if lst2 == None or type(lst2) != list:
        raise ValueError("lst2 must be a list.")
    return list(set(lst1) & set(lst2))