code: def tplot_names():
      
      
      index = 0
      return_names=[]
      for key, _ in data_quants.items():
          if isinstance(data_quants[key].data, list):
              if isinstance(key, str):
                  
                  names_to_print = data_quants[key].name + "  data from: "
                  for name in data_quants[key].data:
                      names_to_print = names_to_print + " " + name
                  print(index, ":", names_to_print)
                  index+=1
          else:
              if isinstance(key, str):
                  names_to_print = data_quants[key].name
                  print(index, ":", names_to_print)
                  index+=1
          return_names.append(names_to_print)
      return return_names
docs: This function will print out and return a list of all current Tplot Variables stored in the memory.  
      
      Parameters:
          None
           
      Returns:
          list : list of str
              A list of all Tplot Variables stored in the memory
              
      Examples:
          >>> import pytplot
          >>> x_data = [1,2,3,4,5]
          >>> y_data = [1,2,3,4,5]
          >>> pytplot.store_data("Variable1", data={'x':x_data, 'y':y_data})
          >>> tnames = pyplot.tplot_names()
          0 : Variable 1