anchor.diff:  
   [source,bash]
   ----
  -perf script -i perf.data | ${FG_HOME}/stackcollapse-perf.pl > out.perf-folded
  -${FG_HOME}/flamegraph.pl out.perf-folded > flamegraph.svg
  +perf script -i perf.data | ${FG_HOME}/stackcollapse-perf.pl | ${FG_HOME}/flamegraph.pl > flamegraph.svg
   ----
   
   image::native-reference-multi-flamegraph-separate-threads.svg[Muti-thread perf flamegraph with separate threads]
  
positive.code: 
  [source,bash]
  ----
  perf script | sed -E "s/thread-[0-9]*/thread/" | ${FG_HOME}/stackcollapse-perf.pl > out.perf-folded
  ${FG_HOME}/flamegraph.pl out.perf-folded > flamegraph.svg
  ----
  
  image::native-reference-multi-flamegraph-joined-threads.svg[Muti-thread perf flamegraph with joined threads]
  
negative.code: 
  [source,bash]
  ----
  perf script -i perf.data | ${FG_HOME}/stackcollapse-perf.pl | ${FG_HOME}/flamegraph.pl > flamegraph.svg
  ----
  
  The flame graph is an svg file that a web browser, such as Firefox, can easily display.
  