input: Write a python function to calculate the absolute difference in days between two dates in the format 'mm/dd/yyyy'.
  assert days_difference('01/01/2020', '01/10/2020') == 9
  assert days_difference('12/25/2020', '01/01/2021') == 7
  assert days_difference('03/15/2021', '02/15/2021') == 28
output: def days_difference(date1, date2):
      from datetime import datetime
  
      format = '%m/%d/%Y'
      d1 = datetime.strptime(date1, format)
      d2 = datetime.strptime(date2, format)
      return abs((d2 - d1).days)