code: function DamerauLevenshteinDistance(source, target, options) {
                  var damLevOptions = underscore.assign(
                      { transposition_cost: 1, restricted: false },
                      options || {},
                      { damerau: true }
                  );
                  return levenshteinDistance(source, target, damLevOptions);
              }
docs: /*
  Returns the Damerau-Levenshtein distance between strings. Counts the distance
  between two strings by returning the number of edit operations required to
  convert `source` into `target`.
  
  Valid edit operations are:
  - transposition, insertion, deletion, and substitution
  
  Options:
  insertion_cost: (default: 1)
  deletion_cost: number (default: 1)
  substitution_cost: number (default: 1)
  transposition_cost: number (default: 1)
  search: boolean (default: false)
  restricted: boolean (default: false)