An [=iterator prototype object=] must have a <code class="idl">next</code> data property with attributes

{ \[[Writable]]: <emu-val>true</emu-val>, \[[Enumerable]]: <emu-val>true</emu-val>, \[[Configurable]]: <emu-val>true</emu-val> }

and whose value is a [=built-in function object=] that behaves as follows:

and whose value is the [=built-in function object=] [$CreateBuiltinFunction$](|nextSteps|, 0, "<code>next</code>", « »),

where |nextSteps| is the following algorithm:

1. Let |interface| be the [=interface=] for which the

[=iterator prototype object=] exists.

An [=asynchronous iterator prototype object=] must have a <code class="idl">next</code> data

property with attributes { \[[Writable]]: <emu-val>true</emu-val>,

\[[Enumerable]]: <emu-val>true</emu-val>, \[[Configurable]]: <emu-val>true</emu-val> }

and whose value is a [=built-in function object=] that behaves as follows:

and whose value is the [=built-in function object=] [$CreateBuiltinFunction$](|nextSteps|, 0, "<code>next</code>", « »),

where |nextSteps| is the following algorithm:

1. Let |interface| be the [=interface=] for which the

[=asynchronous iterator prototype object=] exists.

[=asynchronous iterator prototype object=] must have a <code class="idl">return</code> data

property with attributes { \[[Writable]]: <emu-val>true</emu-val>,

\[[Enumerable]]: <emu-val>true</emu-val>, \[[Configurable]]: <emu-val>true</emu-val> }

and whose value is a [=built-in function object=], taking one argument |value|, that behaves as

follows:

and whose value is the [=built-in function object=] [$CreateBuiltinFunction$](|returnSteps|, 1, "<code>return</code>", « »),

where |returnSteps| is the following algorithm taking one argument |value|:

1. Let |interface| be the [=interface=] for which the

[=asynchronous iterator prototype object=] exists.