@Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (!(o instanceof AlternateSpanList)) return false;
        if (!super.equals(o)) return false;

        AlternateSpanList that = (AlternateSpanList) o;

        if (!childTrees.equals(that.childTrees)) return false;

        return true;
    }
Convenience method to add a span node to the child tree at index i. This is equivalent to calling
<code>
AlternateSpanList.children(i).add(node);
</code>

@param i    index
@param node span node
document/src/main/java/com/yahoo/document/annotation/AlternateSpanList.java