Python: Move predicate closer to its use

Author: yoff

python/ql/lib/semmle/python/dataflow/new/internal/VariableCapture.qll

@@ -17,16 +17,6 @@ private module CaptureInput implements Shared::InputSig<Location> {
     ExprCfgNode() { isExpressionNode(this) }
   }
 
-  private predicate closureFlowStep(ExprCfgNode nodeFrom, ExprCfgNode nodeTo) {
-    // TODO: Other languages have an extra case here looking like
-    //   simpleAstFlowStep(nodeFrom, nodeTo)
-    // we should investigate the potential benefit of adding that.
-    exists(SsaVariable def |
-      def.getAUse() = nodeTo and
-      def.getAnUltimateDefinition().getDefinition().(DefinitionNode).getValue() = nodeFrom
-    )
-  }
-
   class Callable extends Scope {
     predicate isConstructor() { none() }
   }
@@ -95,6 +85,16 @@ private module CaptureInput implements Shared::InputSig<Location> {
     CapturedVariable getVariable() { result = v }
   }
 
+  private predicate closureFlowStep(ExprCfgNode nodeFrom, ExprCfgNode nodeTo) {
+    // TODO: Other languages have an extra case here looking like
+    //   simpleAstFlowStep(nodeFrom, nodeTo)
+    // we should investigate the potential benefit of adding that.
+    exists(SsaVariable def |
+      def.getAUse() = nodeTo and
+      def.getAnUltimateDefinition().getDefinition().(DefinitionNode).getValue() = nodeFrom
+    )
+  }
+
   class ClosureExpr extends Expr {
     ClosureExpr() {
       this.getNode() instanceof CallableExpr