src/bigi/lib/bigi.js
function bnShiftLeft(n) {
  var r = new BigInteger()
  if (n < 0) this.rShiftTo(-n, r)
  else this.lShiftTo(n, r)
  return r
}
function bnShiftLeft(n) {
  var r = new BigInteger()
  if (n < 0) this.rShiftTo(-n, r)
  else this.lShiftTo(n, r)
  return r
}
(public) this << n