The syntax for refresh_completions calls is:
The refresh_completions function is for specifying reloading which programs are installed to locations in your PATH environment variable, it takes zero parameters.
Note: refresh_completions will not pick up modifications to the PATH variable, if added to, removed from or modified then you will need to start a new interactive session for the changes to be picked up.
Example of refresh_completions being used with f++:
Example of refresh_completions being used with n++: