-#define every(A,B) for( A=B; A; A=A->_next)
-#define search(A,B,C) every(A,B) if(C)
-#define find(A,B,C) search(A,B,C) break; if(A)
+#define for_each(A,B) for( A=B; A; A=A->_next)
+#define for_selected(A,B,C) for_each(A,B) if(C)
+#define if_exists(A,B,C) for_selected(A,B,C) break; if(A)