make_command: Helper function to create new command.
Description
make_command is a helper function used by developers to create function for
a new Command object. It should not be used by end users.
Usage
make_command(name, fun, envir = caller_env())
Arguments
- name
- A string of the function name. 
- fun
- A function used to initialize the - Commandobject.
 
- envir
- A environment used to bind the created function.