url = self._resolve_url('/a/creative/uploadcreative')
files = {'file': ('userfile', open(filepath, 'rb'))}
data = {'account_id': account_id}
headers = {'content-type': 'multipart/form-data'}
res = requests.post(url, files=files, data=data, headers=headers)
return res.json
Python Requests Multipart HTTP POST