AttributeError: 'unicode' object has no attribute 'get'

[mrDoctorWho]

| 11.04.2017 (11:08:10) |
Traceback (most recent call last):
  File "library/utils.py", line 24, in execute
    result = handler(*list)
  File "extensions/captcha_forms.py", line 20, in sendCaptcha
    url = captcha.get("img")
AttributeError: 'unicode' object has no attribute 'get'