anchor.diff:      "https://mirror.ibcp.fr/pub/gnu/"
       "https://mirror.dogado.de/gnu/"
       "https://mirror.tochlab.net/pub/gnu/"
  -    "ftp://ftp.funet.fi/pub/mirrors/ftp.gnu.org/gnu/"
   
       # This one is the master repository, and thus it's always up-to-date.
       "https://ftp.gnu.org/pub/gnu/"
  +
  +    "ftp://ftp.funet.fi/pub/mirrors/ftp.gnu.org/gnu/"
     ];
   
     # GCC.
  
positive.code:     # http://bioconductor.fmrp.usp.br/
      # http://mirror.aarnet.edu.au/pub/bioconductor/
      # http://watson.nci.nih.gov/bioc_mirror/
      "http://bioconductor.jp/packages/"
      "https://bioconductor.statistik.tu-dortmund.de/packages/"
      "https://mirrors.ustc.edu.cn/bioc/"
    ];
  
    # Hackage mirrors
  
negative.code:     "https://mirror.chpc.utah.edu/pub/vault.centos.org/"
      "https://mirror.math.princeton.edu/pub/centos-vault/"
      "https://mirrors.tripadvisor.com/centos-vault/"
      "http://mirror.centos.org/centos/"
    ];
  
    # Debian.
    debian = [
      "https://httpredir.debian.org/debian/"
      "https://ftp.debian.org/debian/"
      "ftp://ftp.de.debian.org/debian/"
      "ftp://ftp.fr.debian.org/debian/"
      "ftp://ftp.nl.debian.org/debian/"
      "ftp://ftp.ru.debian.org/debian/"
      "http://archive.debian.org/debian-archive/debian/"
      "ftp://ftp.funet.fi/pub/mirrors/ftp.debian.org/debian/"
    ];
  