import requests

apiKey = 'AxXr'
apiSecret = 'Iq'
url = 'https://api.bitgrail.com/v1/'

req = requests.post(url, payload, headers=headers)

def sign(data):
    signature = hmac.new(apiSecret, data, digestmod=hashlib.sha512).hexdigest()
    return signature

def callAPI(api, payload=dict()):
    url = bitgrailURL % api
    payload['nonce'] = int(time.time() * 1000000)
    payload = '&'.join([kvFormat.format(key, str(payload[key])) for key in payload.keys()])
    headers = {'KEY': apiKey,'SIGNATURE': sign(payload)}

req = requests.post(url, payload, headers=headers)
print req.json()