             }
         }
         if expressions["top"] == nil, expressions["bottom"] != nil {
+            _getters["top"] = nil
             expressions["top"] = "bottom - height"
         }
     }

            }
        }
        guard expression != nil else {
            return
        }
        // Only set constant values once
        if expression.symbols.isEmpty {
            do {

                return // Don't add to expressions arrays for re-evaluations
            } catch {
                // Something went wrong
            }
        }

        // Store expression
        if isViewControllerExpression {
            _viewControllerExpressions[symbol] = expression
        } else if isViewExpression {
