docs: function _parseDockerContentDigest(dcd) {
      if (!dcd) {
          throw new restifyErrors.BadDigestError(
              'missing "Docker-Content-Digest" header');
      }
  
      // E.g. docker-content-digest: sha256:887f7ecfd0bda3...
      var parts = strsplit(dcd, ':', 2);
      if (parts.length !== 2) {
          throw new restifyErrors.BadDigestError(
              'could not parse "Docker-Content-Digest" header: ' + dcd);
      }
  
      var hash;
      try {
          hash = crypto.createHash(parts[0]);
      } catch (hashErr) {
          throw new restifyErrors.BadDigestError(hashErr, fmt(
              '"Docker-Content-Digest" header error: %s: %s',
              hashErr.message, dcd));
      }
      var expectedDigest = parts[1];
  
      return {
          raw: dcd,
          hash: hash,
          algorithm: parts[0],
          expectedDigest: expectedDigest
      };
  }