code: def weeks_per_year(year):
      '''Number of ISO weeks in a year'''
      # 53 weeks: any year starting on Thursday and any leap year starting on Wednesday
      jan1 = jwday(gregorian.to_jd(year, 1, 1))
  
      if jan1 == THU or (jan1 == WED and isleap(year)):
          return 53
      else:
          return 5f weeks_per_year(year):
      '''Number of ISO weeks in a year'''
      # 53 weeks: any year starting on Thursday and any leap year starting on Wednesday
      jan1 = jwday(gregorian.to_jd(year, 1, 1))
  
      if jan1 == THU or (jan1 == WED and isleap(year)):
          return 53
      else:
          return 52
docs: Number of ISO weeks in a year