Parse this person name:

William Johnston (1780-1853, flourished 1810-1821)
user
first_name: William
last_name: Johnston
middle_names: []
temporal:
- start: 1780
  end: 1853
  type: life_span
- start: 1810
  end: 1821
  type: flourished
titles: []
extra_info: []
assistant