• '_prologue_' is an imaginary function that initialize argc, argv
  
• Solid arrow means call edge
  
• Dotted arrow means return edge
  
• Green arrow means branch (pair of call & return)
  
For details, see II-A.'Backbone-Branch Decomposition' section of our paper

Path should NOT include a call edge from 'multi_printf_internal' to 'single_cast_printf' in backbone, because there is a string sanitization in the latter node