Local function definition?

[AlexSWall]

Local function definition?

[faho]

Duplicate of #1799

[faho]

At the moment, all functions in fish are global.

In this specific case, I would recommend making your usage message a variable and then simply printing that at point of use:

set -l usage 'Back up a file or directory.' \
             'Usage:' \
             '' \
	     '    bak [-m/--mv] <path> [optional-postfix]' \
	     '    bak -h/--help'

# and then later:

printf %s\n $usage

(or, you know, make it a separate script and use functions to your heart's content)