code: function(accountsError, accountsResult) {
          const fixedAccountsResult = accountsResult.slice(0);
  
          // if no error, fixed result
          if (!accountsError) {
            fixedAccountsResult.map(function(item) {
              return String(item.toLowerCase());
            });
          }
  
          // fire oldd callback with new fix
          oldCallback(accountsError, fixedAccountsResult);
        }
docs: build fixed callback with lowercased accounts