import json

customer_id = params_kw.get('customer_id', '')
context = {}
if params_kw.get('product_type'):
    context['product_type'] = params_kw.get('product_type')
if params_kw.get('product_name'):
    context['product_name'] = params_kw.get('product_name')
if params_kw.get('request_amount'):
    context['request_amount'] = params_kw.get('request_amount')

result = await get_available_vouchers_api(customer_id, context if context else None)
return json.dumps(result)