code: public Card bankCode(final Integer bankCode) {
          if (bankCode == null) {
              this.bankCode = null;
          } else {
              this.bankCode = String.format("%03d", bankCode);
          }
          return this;
      }
docs: Bank code. See <a
  href="http://es.wikipedia.org/w/index.php?title=CLABE&oldid=71482742#C.C3.B3digo_de_Banco">this</a> for an
  incomplete list as of December, 2013.