diff --git a/include/filters.hpp b/include/filters.hpp
index 426e50b..c404dbb 100644
--- a/include/filters.hpp
+++ b/include/filters.hpp
@@ -1,7 +1,7 @@
 #include <stdint.h>
 
-#include <function.hpp>
+typedef int32_t (*FUN)(int32_t);
 
-auto simplest_lowpass(Function<uint32_t, int16_t> f_in) {
-    Function<uint32_t, int16_t> f_out;
+int32_t stretch(FUN f, float multiplicator, int32_t value) {
+    return f(multiplicator * value);
 }