anchor.diff:    libaribb24: env.LIBARIBB24_VERSION, \
     libass: env.LIBASS_VERSION, \
     libbluray: env.LIBBLURAY_VERSION, \
  -  libcaca: env.LIBCACA_VERSION, \
     libdav1d: env.DAV1D_VERSION, \
     libdavs2: env.DAVS2_VERSION, \
     libfreetype: env.FREETYPE_VERSION, \
  
positive.code:   FONTCONFIG_VERSION=$(pkg-config --modversion fontconfig)  \
    FREETYPE_VERSION=$(pkg-config --modversion freetype2)  \
    FRIBIDI_VERSION=$(pkg-config --modversion fribidi)  \
    LIBCACA_VERSION=$(pkg-config --modversion caca) \
    LIBSAMPLERATE_VERSION=$(pkg-config --modversion samplerate) \
    LIBXML2_VERSION=$(pkg-config --modversion libxml-2.0) \
    SOXR_VERSION=$(pkg-config --modversion soxr) \
  
negative.code:   --enable-libaribb24 \
    --enable-libass \
    --enable-libbluray \
    --enable-libdav1d \
    --enable-libdavs2 \
    --enable-libfreetype \
  