Parse this person name:

Alex van Kempen (1387-1461, flourished 1417-1436)
user
first_name: Alex
last_name: van Kempen
middle_names: []
temporal:
- start: 1387
  end: 1461
  type: life_span
- start: 1417
  end: 1436
  type: flourished
titles: []
extra_info: []
assistant