--- a/service/mqtt_to_rdf/candidate_binding.py	Mon Sep 06 23:04:34 2021 -0700
+++ b/service/mqtt_to_rdf/candidate_binding.py	Mon Sep 06 23:20:23 2021 -0700
@@ -1,5 +1,5 @@
 from dataclasses import dataclass
-from typing import Dict, Iterator
+from typing import Dict, Iterable, Iterator, Union
 
 from prometheus_client import Summary
 from rdflib import BNode, Graph
@@ -16,7 +16,7 @@
         b = " ".join("%s=%s" % (k, v) for k, v in sorted(self.binding.items()))
         return f'CandidateBinding({b})'
 
-    def apply(self, g: Graph) -> Iterator[Triple]:
+    def apply(self, g: Union[Graph, Iterable[Triple]]) -> Iterator[Triple]:
         for stmt in g:
             try:
                 bound = (self._applyTerm(stmt[0]), self._applyTerm(stmt[1]), self._applyTerm(stmt[2]))
@@ -35,6 +35,5 @@
     def addNewBindings(self, newBindings: 'CandidateBinding'):
         for k, v in newBindings.binding.items():
             if k in self.binding and self.binding[k] != v:
-                raise ValueError(
-                    f'conflict- thought {k} would be {self.binding[k]} but another Evaluation said it should be {v}')
-            self.binding[k] = v
\ No newline at end of file
+                raise ValueError(f'conflict- thought {k} would be {self.binding[k]} but another Evaluation said it should be {v}')
+            self.binding[k] = v

--- a/service/mqtt_to_rdf/inference.py	Mon Sep 06 23:04:34 2021 -0700
+++ b/service/mqtt_to_rdf/inference.py	Mon Sep 06 23:20:23 2021 -0700
@@ -48,6 +48,8 @@
             else:
                 self.nonStaticRuleStmts.add(ruleStmt)
 
+        self.nonStaticRuleStmtsSet = set(self.nonStaticRuleStmts)
+
         self.evaluations = list(Evaluation.findEvals(self.graph))
 
     def __repr__(self):
@@ -194,7 +196,8 @@
 
     def verify(self, workingSet: ReadOnlyWorkingSet) -> bool:
         """Can this bound lhs be true all at once in workingSet?"""
-        boundLhs = self.binding.apply(self.lhs.nonStaticRuleStmts - self.usedByFuncs)
+        rem = cast(Set[Triple], self.lhs.nonStaticRuleStmtsSet.difference(self.usedByFuncs))
+        boundLhs = self.binding.apply(rem)
 
         if log.isEnabledFor(logging.DEBUG):
             boundLhs = list(boundLhs)