Parse this person name:

Aron de Keijser, 1240-1280, flourished 1256-1268
user
first_name: Aron
last_name: de Keijser
middle_names: []
temporal:
- start: 1240
  end: 1280
  type: life_span
- start: 1256
  end: 1268
  type: flourished
titles: []
extra_info: []
assistant