code: function tuplesToBuffer (tuples) {
    return fromBuffer(Buffer.concat(tuples.map(tup => {
      const proto = protoFromTuple(tup)
      let buf = Buffer.from(varint.encode(proto.code))
  
      if (tup.length > 1) {
        buf = Buffer.concat([buf, tup[1]]) // add address buffer
      }
  
      return buf
    })))
  }
docs: [[int code, Buffer ]... ] -> Buffer