XF 2.0 Display only first depth subforums

[CNK]

Hello, in home (forum_list template) and default style we have code:

<xf:macro name="sub_nodes_flat" arg-children="!" arg-childExtras="!" arg-depth="3">
    <xf:css src="node_list.less" />
    <xf:if contentcheck="true">
        <div class="node-subNodesFlat">
            <span class="node-subNodesLabel">{{ phrase('sub_forums:') }}</span>
            <ol class="node-subNodeFlatList">
            <xf:contentcheck>
                <xf:macro template="forum_list" name="node_list"
                    arg-children="{$children}"
                    arg-extras="{$childExtras}"
                    arg-depth="{{ $depth + 1 }}" />
            </xf:contentcheck>
            </ol>
        </div>
    </xf:if>
</xf:macro>

How can I change it to display only first depth without children of children etc..?
I tried with arg-depth="{{ $depth}}" and arg-depth="1" but it doesn't work.