--- a/service/mqtt_to_rdf/candidate_binding.py	Mon Sep 20 23:20:46 2021 -0700
+++ b/service/mqtt_to_rdf/candidate_binding.py	Tue Sep 21 22:19:11 2021 -0700
@@ -12,7 +12,7 @@
 INDENT = '    '
 
 
-class BindingConflict(ValueError):
+class BindingConflict(ValueError):  # might be the same as `Inconsistent`
     pass
 
 
@@ -56,11 +56,6 @@
                 raise BindingConflict(f'thought {k} would be {self.binding[k]} but another Evaluation said it should be {v}')
             self.binding[k] = v
 
-    def subtract(self, removeBindings: 'CandidateBinding'):
-        for k, v in removeBindings.binding.items():
-            if k in self.binding:
-                del self.binding[k]
-
     def copy(self):
         return CandidateBinding(self.binding.copy())