def is_dict(obj):
    """
    Checks if a given sequence is a dictionary.

    Parameters
    ----------
    obj : object
        The input argument.

    Returns
    -------
    test result : bool
        The test result of whether seq is a dictionary or not.

    >>> is_dict([1, 2, 3])
    False

    >>> is_dict((1, 2, 3))
    False

    >>> is_dict({'one': 1, 'two': 2, 'three': 3})
    True

    >>> is_dict('foobar')
    False
    """
    return isinstance(obj, dict)
