Parse this person name:

Alexander Johnson, 1254-1304, flourished 1270-1284
user
first_name: Alexander
last_name: Johnson
middle_names: []
temporal:
- start: 1254
  end: 1304
  type: life_span
- start: 1270
  end: 1284
  type: flourished
titles: []
extra_info: []
assistant