docs: def is_date(self):
          """Determine if a data record is of type DATE."""
          dt = DATA_TYPES['date']
          if type(self.data) is dt['type'] and '-' in str(self.data) and str(self.data).count('-') == 2:
              # Separate year, month and day
              date_split = str(self.data).split('-')
              y, m, d = date_split[0], date_split[1], date_split[2]
  
              # Validate values
              valid_year, valid_months, valid_days = int(y) in YEARS, int(m) in MONTHS, int(d) in DAYS
  
              # Check that all validations are True
              if all(i is True for i in (valid_year, valid_months, valid_days)):
                  self.type = 'date'.upper()
                  self.len = None
                  return True