fixup

resolve/plot/sky.py

@@ -22,6 +22,7 @@ import numpy as np
 
 def plot_dirty(fld, file_name):
     import matplotlib.pyplot as plt
+    from matplotlib.colors import CenteredNorm, LogNorm
 
     assert_sky_domain(fld.domain)
     pdom, tdom, fdom, sdom = fld.domain