Restrict visibility of generateImplicitVariable to private

Author: minesh-s-patel

src/main/java/com/regnosys/rosetta/generator/python/expressions/PythonExpressionGenerator.xtend

@@ -260,7 +260,7 @@ class PythonExpressionGenerator {
         return _builder.toString
     }
 
-    protected def String generateImplicitVariable(RosettaImplicitVariable expr, int ifLevel, boolean isLambda) {
+    private def String generateImplicitVariable(RosettaImplicitVariable expr, int ifLevel, boolean isLambda) {
         '''«expr.name»'''
     }