Gets a command by its name.
The name of the command.
The command or undefined if it does not exist.
Registers a new command in the registry.
The name of the command.
The description of the command.
The callback of the command.
The command that was registered.
Registers a new command in the registry.
The name of the command.
The description of the command.
The registry of the command.
The callback of the command.
The command that was registered.
The commands of the registry.