code: function (params) {
    const oThis = this;
  
    params = params || {};
    oThis.erc20Address = params.erc20_address;
    oThis.approverAddress = params.approver_address;
    oThis.approverPassphrase = params.approver_passphrase;
    oThis.approveeAddress = params.approvee_address;
    oThis.toApproveAmount = new BigNumber(params.to_approve_amount);
    oThis.returnType = (params.options || {}).returnType || 'txHash';
  }
docs: Approve for spending Branded Token
  
  @param {object} params
  @param {string} params.erc20_address - Branded token EIP20 address
  @param {string} params.approver_address - Approver address
  @param {string} params.approver_passphrase - Approver passphrase
  @param {string} params.approvee_address - Approvee address
  @param {number} params.to_approve_amount - To Approve amount in weis
  @param {object} params.options - optional params
  
  @constructor