Remove unimplemented(): it's not worth it without *-imports.

Author: darius

csp.py

@@ -1,6 +1,6 @@
 """CSP (Constraint Satisfaction Problems) problems and solvers. (Chapter 6)."""
 
-from utils import count, first, argmin_random_tie
+from utils import argmin_random_tie, count, first
 import search
 
 from collections import defaultdict
@@ -320,11 +320,11 @@ def tree_csp_solver(csp):
 
 
 def topological_sort(xs, x):
-    unimplemented()
+    raise NotImplementedError
 
 
 def make_arc_consistent(Xj, Xk, csp):
-    unimplemented()
+    raise NotImplementedError
 
 # ______________________________________________________________________________
 # Map-Coloring Problems

learning.py

@@ -412,11 +412,11 @@ def decision_list_learning(examples):
     def find_examples(examples):
         """Find a set of examples that all have the same outcome under
         some test. Return a tuple of the test, outcome, and examples."""
-        unimplemented()
+        raise NotImplementedError
 
     def passes(example, test):
         "Does the example pass the test?"
-        unimplemented()
+        raise NotImplementedError
 
     def predict(example):
         "Predict the outcome for the first passing test."

logic.py

@@ -674,11 +674,11 @@ class HybridWumpusAgent(agents.Agent):
     "An agent for the wumpus world that does logical inference. [Figure 7.20]"""
 
     def __init__(self):
-        unimplemented()
+        raise NotImplementedError
 
 
 def plan_route(current, goals, allowed):
-    unimplemented()
+    raise NotImplementedError
 
 # ______________________________________________________________________________
 
@@ -844,7 +844,7 @@ def subst(s, x):
 
 
 def fol_fc_ask(KB, alpha):
-    unimplemented()
+    raise NotImplementedError
 
 
 def standardize_variables(sentence, dic=None):

utils.py

@@ -322,11 +322,6 @@ def DataFile(name, mode='r'):
     return AIMAFile(['aima-data', name], mode)
 
 
-def unimplemented():
-    "Use this as a stub for not-yet-implemented functions."
-    raise NotImplementedError
-
-
 # ______________________________________________________________________________
 # Expressions