# How to produce annotated text, where an original text is contrasted with my comments?

Assume someone sends me a (plain text or LaTeX source) text document. I'm in the position to comment on the text and suggest improvements. I'd like to produce a LaTeX document featuring the original text and my suggestions side by side. The layout should clearly indicate what the original text was and there should be no limit on the amount of text I can add. Does there exist a convenient solution?

Here's an example/mockup:

We conclude that \$A=B\$.
\annotate{Please cite a proper definition of both A and B.
Also note, that the A.B.'s infamous paper uses a notation which contradicts
C.D.'s use of the term A.}
This is trivial.
\annotate{Are you kidding me? Where's the proof?}

Can this be rendered as:

We conclude that \$A=B\$.    Please cite a proper definition
of both A and B.
Also note, that the A.B.'s infamous paper