Pretty format for complex nix-shell inputs

[dmadisetti]

Example:

nix-shell -p 'python38.withPackages(ps: with ps; [ openpyxl pandas pystache jupyter ])'

creates a really messy terminal line:

$ »                  [ ]) jupyter openpyxl pandas ps; pystache python38.withPackages(ps: with
                                                      ^
                                                      |
from any shell ----------------------------------------