In the following excerpt from “one art” by elizabeth bishop, what is the significance of the text in parentheses?

i lost two cities, lovely ones. and, vaster,
some realms i owned, two rivers, a continent.
i miss them, but it wasn’t a disaster.

—even losing you (the joking voice, a gesture
i love) i shan’t have lied. it’s evident
the art of losing’s not too hard to master
though it may look like (write it! ) like disaster.