Return Plone User

    :param user_or_username: Plone user or user id
    :type groupname:  PloneUser/MemberData/str
    :returns: Plone MemberData
    :rtype: object

def get_user(user_or_username=None):
    """Return Plone User

    :param user_or_username: Plone user or user id
    :type groupname:  PloneUser/MemberData/str
    :returns: Plone MemberData
    :rtype: object
    """
    if user_or_username is None:
        return None
    if hasattr(user_or_username, "getUserId"):
        return ploneapi.user.get(user_or_username.getUserId())
    return ploneapi.user.get(userid=u.to_string(user_or_username))