old_contents: courselist = [{'department': 'CS', 'number': 225, 'crn': 35917},
                {'department': 'CS', 'number': 225, 'crn': 35919},
                {'department': 'CS', 'number': 357, 'crn': 53280},
                {'department': 'CS', 'number': 357, 'crn': 63536},
                {'department': 'CS', 'number': 233, 'crn': 63733},
                {'department': 'CS', 'number': 233, 'crn': 64513},
                {'department': 'CS', 'number': 420, 'crn': 53685},
               ]
  
  
new_contents: courselist = [{'department': 'MATH', 'number': 417, 'crn': 65075},
                {'department': 'MATH', 'number': 484, 'crn': 30809},
                {'department': 'MATH', 'number': 347, 'crn': 34395},
               ]
  
  
subject: Update courselist.py