Restore backwards compatibility

plotting.py

@@ -235,7 +235,8 @@ def plot_tune_spectrum(ax, libera_data, xy, turn_range=None, time_range=None, tu
     if fit:
         q = None
         try:
-            fitr = (fit if callable(fit) else fit_lorenzian)(freq, mag)
+            if fit is True: fit = fit_lorenzian
+            fitr = fit(freq, mag)
             if fit in (fit_lorenzian, fit_gaussian):
                 q, w = fitr[0][2], fitr[0][3]
                 if q<np.min(freq) or q>np.max(freq) or w > 0.1: