to get the response back set the below
frappe.flags.message = l_response inside the server script api
The flow goes like this
define a server script api say ‘my_api_server_script’
let’s assume the above script takes two arguments arg 1 and arg2
to fetch the args inside the api script
arg1 = frappe.form_dict.get('arg1')
arg1 = frappe.form_dict.get('arg2')
perform rest of code
finally send the result in frappe.flags
#to get the response from the server side
frappe.flags.message = result
#if you want to use the script from the client side
frappe.response["message"] = result
now you can call the api script from another server script like below
response = frappe.call("my_api_server_script", arg1 = value1, arg2 = value2)
result = response["message"]
Hope this helps