The namespaces do NOT become nested. Use put instead.
The order of the items are preserved.
The items are deduplicated via the id attribute.
Implemented to be cheap but we aware that after this operation the two
namespaces will point to the same elements. A mutation in one of them
will affect both.
Merge the content of other_ns into this.
The namespaces do NOT become nested. Use put instead.
The order of the items are preserved. The items are deduplicated via the id attribute.
Implemented to be cheap but we aware that after this operation the two namespaces will point to the same elements. A mutation in one of them will affect both.