Fig. 6: The test_line() function 

test_line() was probably the most difficult piece of code to get to work, relying as it did 

on so many steps previous steps to have executed correctly for it to do likewise. It also 

exposes  what  I  acknowledge  to  be  a  flaw  in  the  initial  design  of  the  XML  files.  The 

problem is one of functionality: if a user enters a price of  2,500, it is highly unlikely that 

he or she will find very many computers for exactly that price. It is more likely that the 

intended meaning is  less than or equal to  2,500 . Similarly, when someone requires a 

plumber who is available from 8am on a weekday morning, it should be obvious that all 

of  the  plumbers  who  start  work  before  8am are equally available. This issue came to a 

head when trying to define how one would find a plumber at, say, 10pm, since there is no 

truly  efficient  way  to  define  a  timespan  in  the  current  XML  setup. test_line()  currently 

has  a  series  of  fixes  to  make  a  guess  at  what  sort  of  test  should  be  performed  on  a 

43