code: def which(bin_name):
      
  
      with open(os.devnull) as devnull:
          # rc = SP.call(['which', bin_name], stdout=devnull, stderr=devnull)
          rc = SP.call(['which', bin_name])
  
      return rc
docs: :param bin_name: the name of the binary to test for (e.g. vim)
          :returns: True or False depending on wether the binary exists