requirements packages are installed but not accessible

[harobed]

What I do :

$ git clone https://github.com/harobed/nanobox-python-sample.git
$ cd nanobox-python-sample
$ nanobox destroy
$ nanobox  update
$ nanobox update-images
$ nanobox dev

requirements are installed with success https://gist.github.com/harobed/67a3351fc4d880634d8f but :

[gonano@test_nanobox /code]$ ls
Boxfile  README.md  app.py  requirements.txt
[gonano@test_nanobox /code]$ python app.py
Traceback (most recent call last):
  File "app.py", line 1, in <module>
    from flask import Flask
ImportError: No module named flask
[gonano@test_nanobox /code]$ cat requirements.txt
flask
[gonano@test_nanobox /code]$ pip
bash: pip: command not found

Problems :

• flask package isn't accessible
• where is virtualenv ?
• where is pip ?

Best regards, Stephane