Parse this person name:

Robert Stephenson, 1431-1511, flourished 1457-1487
user
first_name: Robert
last_name: Stephenson
middle_names: []
temporal:
- start: 1431
  end: 1511
  type: life_span
- start: 1457
  end: 1487
  type: flourished
titles: []
extra_info: []
assistant