def isextension(filename, ext):
    """Does the filename end with the extension ext? 
    
    >>> isextension('/path/to/myfile.json', 'json') == True
    >>> isextension('/path/to/myfile.json', '.json') == True
    >>> isextension('/path/to/myfile.json', '.pkl') == False

    """
    return filename.endswith(ext)