10 print "<<< ref#(btrack)=", sys.getrefcount(btrack)
 
   11 bstep= btrack.GetStep2()
 
   12 print "<<< ref#(btrack, bstep)=",\
 
   13       sys.getrefcount(btrack),\
 
   14       sys.getrefcount(bstep)
 
   16 print "<<< delete bstep" 
   17 print "<<< ref#(btrack)=", sys.getrefcount(btrack)
 
   21 cstep= btrack.GetStep2()
 
   23 print "<<< previous step is still remain?" 
   27 print "--- stderr ---"