code: def line_type(self, line_type):
          
          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
docs: 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