def convert_positional_argument(self, index, arg_value):
<EOL>if self._has_self:<EOL><INDENT>if index == <NUM_LIT:0>:<EOL><INDENT>return arg_value<EOL><DEDENT>index -= <NUM_LIT:1><EOL><DEDENT>arg_name = self.arg_names[index]<EOL>return self.convert_argument(arg_name, arg_value)<EOL>
Convert and validate a positional argument.

        Args:
            index (int): The positional index of the argument
            arg_value (object): The value to convert and validate

        Returns:
            object: The converted value.