code: def session_array(slots):
      
      # Flatten the list: this assumes that the sessions do not share slots
      sessions = sorted(set([slot.session for slot in slots]))
      array = np.zeros((len(sessions), len(slots)))
      for col, slot in enumerate(slots):
          array[sessions.index(slot.session), col] = 1
      return array
docs: Return a numpy array mapping sessions to slots
  
      - Rows corresponds to sessions
      - Columns correspond to slots