How to fix "TypeError: unsupported operand type(s) for +: 'NoneType' and 'str'"?

In python3, print is a function that returns None. So, the line:

print ("number of donuts: " ) +str(count)

you have None + str(count).

What you probably want is to use string formatting:

print ("Number of donuts: {}".format(count))

Your parenthesis is in the wrong spot:

print ("number of donuts: " ) +str(count)
                            ^

Move it here:

print ("number of donuts: " + str(count))
                                        ^

Or just use a comma:

print("number of donuts:", count)