+/**
+ * This method is defined to be in line with behaviour of function::return_type()
+ */
+ex function::eval_ncmul(const exvector & v) const
+{
+ // If this function is called then the list of arguments is non-empty
+ // and the first argument is non-commutative, see function::return_type()
+ return seq.begin()->eval_ncmul(v);
+}
+