diff --git a/src/variables.jl b/src/variables.jl
index 7776feedf8ac92a496f0930e0dadb17b66e0cf14..85f851f4f8019b2e2fdbf9bb628d79df4857e09e 100644
--- a/src/variables.jl
+++ b/src/variables.jl
@@ -172,6 +172,9 @@ Instead, the `bmat` and `bval` should be constrained for specific `Pathways`
 function bmat_gradient end
 
 
+function effective_time end
+
+
 """
     VariableNotAvailable(building_block, variable, alt_variable)