skip entries that cannot be written with a printed warning

grum/io.py

@@ -5,7 +5,10 @@ def write_dict(fn, d):
     d = flatten_dict(d)
     with h5py.File(fn, "w") as f:
         for k, v in d.items():
-            f[k] = v
+            try:
+                f[k] = v
+            except Exception:
+                print("could not store:", k, "<<", v)
 
 
 def flatten_dict(d, parent="", sep="/"):