code: def exists():
      
  
      if env():
          cij.err("cij.nvm.exists: Invalid NVMe ENV.")
          return 1
  
      nvm = cij.env_to_dict(PREFIX, EXPORTED + REQUIRED)
  
      cmd = ['[[ -b "%s" ]]' % nvm["DEV_PATH"]]
      rcode, _, _ = cij.ssh.command(cmd, shell=True, echo=False)
  
      return rcode
docs: Verify that the ENV defined NVMe device exists