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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def line_type(self, line_type):
 """Sets the line_type of this ChartSettings. Plot interpolation type. linear is default # noqa: E501 :param line_type: The line_type of this ChartSettings. # noqa: E501 :type: str """

        allowed_values = ["linear", "step-before", "step-after", "basis", "cardinal", "monotone"]  # noqa: E501
        if line_type not in allowed_values:
            raise ValueError(
                "Invalid value for `line_type` ({0}), must be one of {1}"  # noqa: E501
                .format(line_type, allowed_values)
            )

        self._line_type = line_type