optional_depends libusb                      \
                 "--enable-libusb"           \
                 "--disable-libusb"          \
                 "Enable libusb support"     &&
optional_depends libgphoto2                  \
                 "--with-gphoto2"            \
                 "--without-gphoto2"         \
                 "Enable libgphoto2 backend" &&
optional_depends tetex                      \
                 "--enable-translations"     \
                 "--disable-translations"    \
                 "Build translated documentation"
