code: def plot(self,**kwargs):
          
          try:
              import matplotlib.pyplot as plt
          except Exception as e:
              raise Exception("error importing matplotlib: {0}".format(str(e)))
  
          ax = kwargs.pop("ax",plt.subplot(111))
          x = np.linspace(0,self.a*3,100)
          y = self.inv_h(x)
          ax.set_xlabel("distance")
          ax.set_ylabel("$\gamma$")
          ax.plot(x,y,**kwargs)
          return ax
docs: get a cheap plot of the Vario2d
  
          Parameters
          ----------
          **kwargs : (dict)
              keyword arguments to use for plotting
  
          Returns
          -------
          ax : matplotlib.pyplot.axis
  
          Note
          ----
          optional arguments in kwargs include
          "ax" (existing matplotlib.pyplot.axis).  Other
          kwargs are passed to matplotlib.pyplot.plot()