code: def validate_day(year, month, day):
          
  
          max_days = LONG_MONTH
          if month == FEB:
              max_days = FEB_LEAP_MONTH if ((year % 4 == 0) and (year % 100 != 0)) or (year % 400 == 0) else FEB_MONTH
          elif month in MONTHS_30:
              max_days = SHORT_MONTH
          return 1 <= day <= max_days
docs: Validate day.