How to localize function help string obtained from docstring?

[rffontenelle]

Considering the following code, the _("""Print FILENAME.""") causes the string "Print FILENAME." to be translateable, but its translation won't be printed in the command's --help (simply blank); and if I leave """Print FILENAME.""" as is, the string doesn't get extracted to the translation files and the English string is correctly shown in the command's --help.

# File: my-project/i18n.py

import gettext
import os

PACKAGE = 'my-project'
LOCALE_DIR = os.path.join(os.path.dirname(__file__), 'locale')
LANGUAGE = os.getenv('LANG', 'C').split('.')[0]

translation = gettext.translation(PACKAGE, localedir=LOCALE_DIR, languages=[LANGUAGE], fallback=True)
_ = translation.gettext

# file: my-project/cli.py

from .i18n import _

@click.command()
@click.argument('filename')
def touch(filename):
    _("""Print FILENAME.""")
    click.echo(filename)

xgettext --keyword=_ --output po/my-project.pot my-project/cli.py