(classic)liu-xiao-guo@localhost:~/apps/grovepi$ snapcraft 
Use of build-properties in the schema is deprecated.
Plugins should now implement get_build_properties
DEPRECATED: The 'copy' plugin's functionality has been replaced by the 'dump' plugin, and it will soon be removed.
Use of build-properties in the schema is deprecated.
Plugins should now implement get_build_properties
Preparing to pull py 
Pulling py 
'i2clib' has prerequisites that need to be staged: py
Preparing to build py 
Building py 
Staging py 
Preparing to pull i2clib 
Pulling i2clib 
Preparing to pull mosquitto 
Err http://localhost:9999/ubuntu-ports xenial InRelease                                               
  Could not connect to localhost:9999 (127.0.0.1). - connect (111: Connection refused) [IP: 127.0.0.1 9999]
Err http://localhost:9999/ubuntu-ports xenial-updates InRelease                                       
  Unable to connect to localhost:9999: [IP: 127.0.0.1 9999]                                           
Err http://localhost:9999/ubuntu-ports xenial-backports InRelease                                     
  Unable to connect to localhost:9999: [IP: 127.0.0.1 9999]                                           
Err http://localhost:9999/ubuntu-ports xenial-security InRelease                                      
  Unable to connect to localhost:9999: [IP: 127.0.0.1 9999]                                           
Fetched 0 B in 0s (0 B/s)                                                                             

(classic)liu-xiao-guo@localhost:~/apps/grovepi$ exit
logout
liu-xiao-guo@localhost:~$ cd /var/snap/packageproxy/
3/       common/  current/ 
liu-xiao-guo@localhost:~$ cd /var/snap/packageproxy/3/
liu-xiao-guo@localhost:/var/snap/packageproxy/3$ ls
approx.conf  config.yaml  hosts.allow  hosts.deny  lockfile.lock  var
liu-xiao-guo@localhost:/var/snap/packageproxy/3$