How could one emulate namespace in C?

Question

In C++ one might use namespace to keep independent groups working in the same code base from inadvertently creating functions with the same name and thus creating a conflict. My question is, before the idea of namespace comes out, how might one emulate namespace in C.

Answer 1

By naming things differently, e.g.:

void namespace_group_function();

gtk+ is a prime example for this conventional style:

GtkWidget* gtk_window_new(GtkWindowType type);