Specifies a session from which to read or to which to write when copying cookies. This can be the default session (if you specify "default" as a value), or the session for a named partition (e.g., { partition: "my-partition" }). Partition names are wrapped in objects to prevent a potential collision between the "default" literal, which signifies the default session, and a partition named "default".

• "default"
• { partition: string }