error on the newest version of ubuntu core

(classic)ubuntu@localhost:~/software$ snapcraft snap
pyversions -d
/tmp/tmprrqaops6: 2: exec: pyversions: not found
Command '['/bin/sh', '/tmp/tmprrqaops6', 'pyversions', '-d']' returned non-zero exit status 127
(classic)ubuntu@localhost:~/software$



name: app
version: 0.1
summary: app
description: app

parts:
   flask:
      plugin: python2
      source: .