code: def zlim(name, min, max):
      
      if name not in data_quants.keys():
          print("That name is currently not in pytplot.")
          return
      
      temp_data_quant = data_quants[name]
      temp_data_quant.zaxis_opt['z_range'] = [min, max]
      
      return
docs: This function will set the z axis range displayed for a specific tplot variable.
      This is only used for spec plots, where the z axis represents the magnitude of the values
      in each bin.  
      
      Parameters:
          name : str
              The name of the tplot variable that you wish to set z limits for.  
          min : flt
              The start of the z axis.
          max : flt
              The end of the z axis.   
              
      Returns:
          None
      
      Examples:
          >>> # Change the z range of Variable1 
          >>> import pytplot
          >>> x_data = [1,2,3]
          >>> y_data = [ [1,2,3] , [4,5,6], [7,8,9] ]
          >>> v_data = [1,2,3]
          >>> pytplot.store_data("Variable3", data={'x':x_data, 'y':y_data, 'v':v_data})
          >>> pytplot.zlim('Variable1', 2, 3)