anchor.diff:  	$(RM) *.o *.so*
   ----
   
  -<1> the name <1> and version of the library are just parameters
  +<1> the name 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
  
positive.code: which--not too surprisingly--has greetings as its main purpose. 
  
  [source,c]
  .`foo.h`
  ----
  #ifndef FOO_H
  #define FOO_H
  
negative.code: and test it using a quick C executable:
  
  [source,c]
  .foo_test.c
  ----
  #include "foo.h"
  
  