code: function convertData2Hexd (data) {
    if (!isHexString(data)) {
      var hex = ''
      for (var i = 0; i < data.length; i++) {
        hex += data.charCodeAt(i).toString(16)
      }
      return '0x' + hex
    }
    return data
  }
docs: Convert to hexadecimal for data property of SendTransaction
  @param {*} data