Fix doctest after renaming type_to_histtype

nnfwtbn/plot.py

@@ -38,9 +38,9 @@ def _type_to_histtype(type):
     """
     Returns the matplotlib histogram type for a given process plotting type.
 
-    >>> type_to_histtype("fill")
+    >>> _type_to_histtype("fill")
     'stepfilled'
-    >>> type_to_histtype("line")
+    >>> _type_to_histtype("line")
     'step'
     """
     type_map = {"fill": "stepfilled", "line": "step"}