Debugging in shell

Let's say your fellow student who also learns programming has written a piece of code but it doesn't work correctly. And as you now know how to debug, they asked you to help find an error.

You understand that the bug is in the function which_type():

def which_type(el):
    """ This function is needed to control which arguments are passed further. """
    if isinstance(type(el), 'str'):             # 3rd line
        return('The string has been given.')    # 4th line
    else:                                       # 5th line
        return('Another type has been given.')  # 6th line

It is activated in the following piece of code:

for element in [3, 'three', ['3'], {'three'}]:
    print(which_type(element))

Run this code in IDLE Shell (don't forget to copy the function first!). Use the debugging tools to find the error. At which step does the program behave not as expected? In which line of the function is the problem? Write only the number of the line in the text field below.

If you already see what the problem with the code is, don't just write the answer. The point of this topic is to learn how to use IDLE's debugger, so use this opportunity to practice.