anchor.diff:  ----
   
   [source,c]
  -.`foo.c`
  +.foo.c
   ----
   
   #include "foo.h"
  
positive.code: 	$(RM) *.o *.so*
  ----
  
  <1> the name <1> and version of the library are just parameters
  <2> it creates a shared object with a proper soname
  <3> it compiles the library with debugging symbols, optimization and 
    strict error checking
  
negative.code: which--not too surprisingly--has greetings as its main purpose. 
  
  [source,c]
  .foo.h
  ----
  #ifndef FOO_H
  #define FOO_H
  