he type of the attribute.  In Python 3.6 or greater, the
        preferred method to specify the type is using a variable annotation
        (see :pep:`526`).
        This argument is provided for backward compatibility.
        Regardless of the approach used, the type will be stored on
        ``Attribute.type``.

        Please note that ``attrs`` doesn't do anything with this metadata by
        itself. You can use it as part of your own code or for
        `static type checking <types>`.
    :param kw_only: Make this attribute keyword-only (Python 3+)
        in the generated ``__init__`` (if ``init`` is ``False``, this
        parameter is ignored).
    :param on_setattr: Allows to overwrite the *on_setattr* setting from
        `attr.s`. If left `None`, the *on_setattr* value from `attr.s` is used.
        Set to `attrs.setters.NO_OP` to run **no** `setattr` hooks for this
        attribute -- regardless of the setting in `attr.s`.
    :type on_setattr: `callable`, or a list of callables, or `None`, or
        `attrs.setters.NO_OP`

    .. versionadded:: 15.2.0 *convert*
    .. versionadded:: 16.3.0 *metadata*
    .. versionchanged:: 17.1.0 *validator* can be a ``list`` now.
    .. versionchanged:: 17.1.0
       *hash* is ``None`` and therefore mirrors *eq* by default.
    .. versionadded:: 17.3.0 *type*
    .. deprecated:: 17.4.0 *convert*
    .. versionadded:: 17.4.0 *converter* as a replacement for the deprecated
       *convert* to achieve consistency with other noun-based arguments.
    .. versionadded:: 18.1.0
       ``factory=f`` is syntactic sugar for ``default=attr.Factory(f)``.
    .. versionadded:: 18.2.0 *kw_only*
    .. versionchanged:: 19.2.0 *convert* keyword argument removed.
    .. versionchanged:: 19.2.0 *repr* also accepts a custom callable.
    .. deprecated:: 19.2.0 *cmp* Removal on or after 2021-06-01.
    .. versionadded:: 19.2.0 *eq* and *order*
    .. versionadded:: 20.1.0 *on_setattr*
    .. versionchanged:: 20.3.0 *kw_only* backported to Python 2
    .. versionchanged:: 21.1.0
       *eq*, *order*, and *cmp* also accept a custom callable
    .. versionchanged:: 21.1.0 *cmp* undeprecated
    TNFú6Invalid value for hash.  Must be True, False, or None.z=The `default` and `factory` arguments are mutually exclusive.z*The `factory` argument must be a callable.)Ú