The DRF documentation provides clear instructions on [how to create a custom permission](http://www.django-rest-framework.org/api-guide/permissions/#custom-permissions), offering the following code sample:

```
from rest_framework import permissions

class BlacklistPermission(permissions.BasePermission):
"""
Global permission check for blacklisted IPs.
"""

    def has_permission(self, request, view):
        ip_addr = request.META['REMOTE_ADDR']
        blacklisted = Blacklist.objects.filter(ip_addr=ip_addr).exists()
        return not blacklisted

```

By default this gives the following response when the permission check function return `False`.

> 
> HTTP 403 FORBIDDEN  
> 
>  Content-Type: application/json  
> 
>  Vary: Accept  
> 
>  Allow: GET, POST, HEAD, OPTIONS 
> 
> 
> {
>  "detail": "You do not have permission to perform this action."
>  }
> 
> 
> 

I would like to change the "detail" section above, offering a more developer-friendly error message. How could I do this, ensuring the message is presented each time the permission check fails?