Of course, over a century of medical evidence has firmly shown that the removal of the human appendix after infancy has no obvious ill effects (apart from surgical complications, Williams and Myers 1994 ). Earlier reports of an association between appendectomy and certain types of cancer were artifactual ( Andersen and Isager 1978 ; Gledovic and Radovanovic 1991 ; Mellemkjaer et al. 1998 ). In fact, congenital absence of the appendix also appears to have no discernable effect. From investigative laparoscopies for suspected appendicitis, many people have been found who completely lack an appendix from birth, apparently without any physiological detriment ( Anyanwu 1994 ; Chevre et al. 2000 ; Collins 1955 ; Hei 2003 ; Host et al. 1972 ; Iuchtman 1993 ; Kalyshev et al. 1995 ; Manoil 1957 ; Pester 1965 ; Piquet et al. 1986 ; Ponomarenko and Novikova 1978 ; Rolff et al. 1992 ; Saave 1955 ; Shperber 1983 ; Tilson and Touloukian 1972 ; Williams and Myers 1994 , p. 22).
If that special target is defined then in between the two phases mentioned above, right at the end of the read-in phase, all the prerequisites of the targets defined after the special target are expanded a second time . In most circumstances this secondary expansion will have no effect, since all variable and function references will have been expanded during the initial parsing of the makefiles. In order to take advantage of the secondary expansion phase of the parser, then, it’s necessary to escape the variable or function reference in the makefile. In this case the first expansion merely un-escapes the reference but doesn’t expand it, and expansion is left to the secondary expansion phase. For example, consider this makefile: