Type annotation for preprocess_plugins

Co-authored-by: Bagaev Dmitry <[email protected]>

Author: wouterwln

src/graph_engine.jl

@@ -2132,7 +2132,7 @@ Calls a plugin specific logic after the model has been created. By default does
 """
 postprocess_plugin(plugin, model) = nothing
 
-function preprocess_plugins(type::AbstractPluginTraitType, model::Model, context::Context, label::NodeLabel, nodedata::NodeData, options)
+function preprocess_plugins(type::AbstractPluginTraitType, model::Model, context::Context, label::NodeLabel, nodedata::NodeData, options)::Tuple{NodeLabel, NodeData}
     plugins = filter(type, getplugins(model))
     return foldl(plugins; init = (label, nodedata)) do (label, nodedata), plugin
         return preprocess_plugin(plugin, model, context, label, nodedata, options)