def scrub_output(nb):
    """Removes output cells from notebook
       
    Arguments:
        nb {notebook} -- Notebook
    
    Returns:
        notebook -- Notebook with scrubbed output cells
    """
    for cell in nb['cells']:
        if cell['cell_type'] != 'code':
            continue
        cell['outputs'] = []
        cell['execution_count'] = None
    return nb