code: public static float compare(final int numOfBits, final String str1,
              final String str2) {
          return compare(numOfBits, BaseEncoding.base64().decode(str1),
                  BaseEncoding.base64().decode(str2));
      }
docs: Compare base64 strings for MinHash.
  
  @param numOfBits The number of MinHash bits
  @param str1 MinHash base64 string
  @param str2 MinHash base64 string
  @return similarity (0 to 1.0f)