code: function BigInteger(a, b) {
      if (a != null) {
          if ("number" == typeof a) {
              this.fromNumber(a, b);
          } else if (Buffer.isBuffer(a)) {
              this.fromBuffer(a);
          } else if (b == null && "string" != typeof a) {
              this.fromByteArray(a);
          } else {
              this.fromString(a, b);
          }
      }
  }
docs: (public) Constructor