docs: 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';
  }