@staticmethod
def _vec_2tuple(obj):
    """
        Return a tuple from a list or tuple object.

        :param obj: Object
        :type obj: list, tuple
        :return: Tuple
        :rtype: tuple
        """
    if isinstance(obj, tuple):
        return obj
    elif isinstance(obj, list):
        return obj[0], obj[1]
    else:
        raise ValueError('object is not a 2 vector')
