code: def convert_field_value(type_, value):
      
      if value == ".":
          return None
      elif type_ in ("Character", "String"):
          if "%" in value:
              for k, v in record.UNESCAPE_MAPPING:
                  value = value.replace(k, v)
          return value
      else:
          try:
              return _CONVERTERS[type_](value)
          except ValueError:
              warnings.warn(
                  ("{} cannot be converted to {}, keeping as " "string.").format(value, type_),
                  CannotConvertValue,
              )
              return value
docs: Convert atomic field value according to the type