Python Flask Basics Character Builder Cookies

If request is a dictionary object, why must dict be called on it before turning it into a json string?

response.set_cookie("bunny", json.dumps(dict(request.form.items())))
# I tried this w/out the dict(), with dict(form..items)
# this snippet only seems to work this way
# although I believe I read that request is a dictionary obj
# it seems odd to me that a dictionary obj 
# would need to be wrapped in a dictionary function to work