code: def executable(self):
          
          exe = util.find_executable('bin/symbiotic', exitOnError=False)
          if exe:
              return exe
          else:
              # this may be the old version of Symbiotic
              return OldSymbiotic.executable(self)
docs: Find the path to the executable file that will get executed.
          This method always needs to be overridden,
          and most implementations will look similar to this one.
          The path returned should be relative to the current directory.