code: async function (toApproveAmount) {
  
      const oThis = this
      ;
  
      const approveRsp = await simpleToken.approve(
        stakerAddress,
        stakerPassphrase,
        openSTValueContractAddress,
        toApproveAmount,
        oThis.runInAsync
      );
  
      return Promise.resolve(approveRsp);
  
    }
docs: Approve OpenSTValue contract for starting the stake and mint process.
  
  @param {BigNumber} toApproveAmount - this is the amount which is used for approval
  
  @return {promise<result>}
  @private
  @ignore