def plot_volume_temperature(self, exp_data=None):
    import matplotlib.pyplot as plt
    (fig, ax) = plt.subplots()
    self._plot_volume_temperature(ax, exp_data=exp_data)
    return plt
def plot_volume_temperature(self, exp_data=None):
    import matplotlib.pyplot as plt
    (fig, ax) = plt.subplots()
    self._plot_volume_temperature(ax, exp_data=exp_data)
    return plt