$ perl  key_source.pl
Remaining keys (before the while loop):
$VAR1 = {
          '0000046FD530A338D03422C7D0D16A9EE087ECD9' => '67c0da2da88a23a803733cea951e84974b34d029',
          '00000142988AFA836117B1B572FAE4713F200567' => 'b05be3e17bb9987ffb368696ee916dd9b9c2f9b3',
          '000001BCBC3B7C8C6E5FC59B686D3568132D218C' => 'd09565280ebae0a37ca9385bc39c0a777a446554'
        };
Required sources :
$VAR1 = {
          '50edd315b9217345b1728c38b02657df42043197' => 1,
          '36bed8bdb6d66fb67f409166f5db64b02199812f' => 1,
          '55b8ece03f4935f9be667e332d52f7db3e17b809' => 1,
          'b05be3e17bb9987ffb368696ee916dd9b9c2f9b3' => 1,
          '67c0da2da88a23a803733cea951e84974b34d029' => 1,
          '2adeac692d450c54f8830014ee6cbe3a958c1e60' => 1,
          'd09565280ebae0a37ca9385bc39c0a777a446554' => 1,
          '3c4b0a3c1acf6e03111805a0d8b4e879df112b7a' => 1,
          '691845459c0ad35b28cce4dffc0e3ee8912fb0f5' => 1,
          '0c5e6cdb06c52160ded398d17392246269165e0a' => 1,
          '2f214516cdcab089e83f3e5094928fe9611f2f51' => 1,
          'cd15550344b5b9c2785a13ef9583015f267ad667' => 1
        };


Remaining keys:
$VAR1 = {};