anchor.diff: -{ stdenv, fetchurl, ncurses, which, perl
  +{ stdenv, fetchurl, fetchpatch, ncurses, which, perl
   , gdbm ? null
   , openssl ? null
   , cyrus_sasl ? null
  +, gnupg ? null
   , gpgme ? null
   , kerberos ? null
   , headerCache  ? true
   , sslSupport   ? true
   , saslSupport  ? true
  +, smimeSupport ? false
  +, gpgSupport   ? false
   , gpgmeSupport ? true
   , imapSupport  ? true
   , withSidebar  ? true
  
positive.code:     sha256 = "1c8vv4anl555a03pbnwf8wnf0d8pcnd4p35y3q8f5ikkcflq76vl";
    };
  
    patchPhase = optionalString (openssl != null) ''
      sed -i 's#/usr/bin/openssl#${openssl}/bin/openssl#' smime_keys.pl
    '';
  
    buildInputs =
      [ ncurses which perl ]
  
negative.code: assert headerCache  -> gdbm       != null;
  assert sslSupport   -> openssl    != null;
  assert saslSupport  -> cyrus_sasl != null;
  assert smimeSupport -> openssl    != null;
  assert gpgSupport   -> gnupg      != null;
  assert gpgmeSupport -> gpgme      != null && openssl != null;
  
  with stdenv.lib;
  
  