ImportError: cannot import name MergeDict

I am trying to update django 1.7 to 1.9.12.
After updating django I am getting below error stack.

```
 File "/home/abc/Documents/venv/rest_api/api/all_utils/goal_utils.py", line 3, in <module>
    from rest_framework.request import MergeDict
ImportError: cannot import name MergeDict

```

I have installed **djangorestframework==3.5.3**.

How can I solve this error?
Thanks in advance.
