[V8] TypeError: keys must be a string

I am trying to implement Stripe in the system. The thing is that when I try from Python project, it works but with Frappe, it does not work.

The Code:

import stripe

stripe.api_key = StaticVars().stripe_api
return frappe.local.response
customer = stripe.Charge.list()

ERROR message:

Traceback (most recent call last):
File “/usr/lib/python2.7/runpy.py”, line 174, in _run_module_as_main
main”, fname, loader, pkg_name)
File “/usr/lib/python2.7/runpy.py”, line 72, in _run_code
exec code in run_globals
File “/home/frappe/frappe-bench/apps/frappe/frappe/utils/bench_helper.py”, line 94, in
main()
File “/home/frappe/frappe-bench/apps/frappe/frappe/utils/bench_helper.py”, line 18, in main
click.Group(commands=commands)(prog_name=‘bench’)
File “/home/frappe/frappe-bench/env/local/lib/python2.7/site-packages/click/core.py”, line 722, in call
return self.main(*args, **kwargs)
File “/home/frappe/frappe-bench/env/local/lib/python2.7/site-packages/click/core.py”, line 697, in main
rv = self.invoke(ctx)
File “/home/frappe/frappe-bench/env/local/lib/python2.7/site-packages/click/core.py”, line 1066, in invoke
return _process_result(sub_ctx.command.invoke(sub_ctx))
File “/home/frappe/frappe-bench/env/local/lib/python2.7/site-packages/click/core.py”, line 1066, in invoke
return _process_result(sub_ctx.command.invoke(sub_ctx))
File “/home/frappe/frappe-bench/env/local/lib/python2.7/site-packages/click/core.py”, line 895, in invoke
return ctx.invoke(self.callback, **ctx.params)
File “/home/frappe/frappe-bench/env/local/lib/python2.7/site-packages/click/core.py”, line 535, in invoke
return callback(*args, **kwargs)
File “/home/frappe/frappe-bench/env/local/lib/python2.7/site-packages/click/decorators.py”, line 17, in new_func
return f(get_current_context(), *args, **kwargs)
File “/home/frappe/frappe-bench/apps/frappe/frappe/commands/init.py”, line 24, in _func
ret = f(frappe._dict(ctx.obj), *args, **kwargs)
File “/home/frappe/frappe-bench/apps/frappe/frappe/commands/utils.py”, line 120, in execute
print(json.dumps(ret))
File “/usr/lib/python2.7/json/init.py”, line 244, in dumps
return _default_encoder.encode(obj)
File “/usr/lib/python2.7/json/encoder.py”, line 207, in encode
chunks = self.iterencode(o, _one_shot=True)
File “/usr/lib/python2.7/json/encoder.py”, line 270, in iterencode
return _iterencode(o, 0)
TypeError: keys must be a string