+[SReturn]
+
+<return e,c> <= <e,c> => <v,c'>, c'[ret->v], STOP
+
+Evaluate the expression, add the value as return value to the state and stop the execution of the state
+
+[Func]
+
+<t i (ds) ss, c> => c[i-><ds,ss>]
+
+Adds the function i with parameters ds and body ss to the context
+
+[Program]
+
+<fs ss, c> => c'' <= c[fs] => c', <ss,c'> => c''
+
+Add all the function to the context and execute the statements in this context