Share flags or options from super command to subcommand

Say I have a command named command that accepts top-level flags (say -a & -b).

How can I share the Bool value for each flag from the Command: ParsableCommand to Subcommand1: ParsableCommand, Subcommand2: ParsableCommand, etc.

e.g.:

command -a subcommand1

The Subcommand1 Swift code needs to know that Command.a == true but Command.b == false.