Return type of order parameter at the index provided and
        represented by a short string.

        Args:
            index (int): index of order parameter for which type is
                to be returned.
        Returns:
            str: OP type.

def get_type(self, index):

        """
        Return type of order parameter at the index provided and
        represented by a short string.

        Args:
            index (int): index of order parameter for which type is
                to be returned.
        Returns:
            str: OP type.
        """
        if index < 0 or index >= len(self._types):
            raise ValueError("Index for getting order parameter type"
                             " out-of-bounds!")
        return self._types[index]