What does the @ in poetry add pendulum@^2.0.5 in a docs example mean? #5136

• I have searched the issues of this repo and believe that this is not a duplicate.

Issue

In the CLI docs page (cli.md), the documentation for add gives two examples for specifying a constraint:

poetry add pendulum@^2.0.5
poetry add "pendulum>=2.0.5"

In the first line, what is the meaning of @ in addition to ^? Is this a symbol that modifies the behaviour of ^, some shell-specific escape sequence (I know that < and > can be troublesome), or just a small typo? It's never referenced again in the accompanying text, or the Dependency Specification docs page (dependency-specification.md).

(It's been in the example ever since it was first added in c6a2d6e)

My reason for looking at this is that I've had another developer a little confused why poetry add foo@1.2.3 isn't working to update a required version. I think it's simply that @ isn't a valid specifier, and they've copied (part of) this example.