from typing import Counter


def commonElements(x, y):
    """
    Find the common elements in two lists.
    Parameters
    ----------
    x, y : list of any
        The two lists of which we want the common elements.
    
    Returns
    -------
    list of any
        The list of common elements. The same elements will only appear once.
    """
    xc = Counter(x)
    yc = Counter(y)
    return list((xc & yc).elements())