Retrieving variable from other codelet using string containing variable "path".

Hello.

I am trying to parse a variable from another codelet using ISAAC_PARAM().
In carter (latest nightly build) they do something similar in:

"manual_mode_channel": "commander.robot_remote/isaac.navigation.RobotRemoteControl/manual_mode"
"var_rx_speed_pos": "$(fullname imu_odometry.odometry/DifferentialBaseWheelImuOdometry/speed_p)"

But this seems to only pass a string so in isaac::planner::DifferentialBaseControl and isaac::navigation::GoTo,
there must be some code to convert these strings to a bool for their respective variable.

How is this done?