if validate

= view_marker

> if [[ -v {{ name.upcase }} && -n $(validate_{{ validate }} "${{ name.upcase }}") ]]; then
>   printf "{{ strings[:environment_variable_validation_error] }}\n" "{{ usage_string }}" "$(validate_{{ validate }} "${{ name.upcase }}")" >&2
>   exit 1
> fi
>

end