Illustrated below is an example of a flow with the Record Generator as the source step and the HTTP Service step as the destination step.
The image below is the Record Generator step which is populated with the Base64 string record.
Illustrated in the image below is the code that is used in the Calculator step.
Below is the code to copy and paste in the Calculator step:
let inputRecord=input.record;
return createBuffer(inputRecord.base64File,‘base64’)