Re: [help-texinfo] Inserting Code Sample

[Karl Berry]

    can see some black blocks at the end of the lines.

TeX is telling you those lines are too long (reported as "overfull", in
the terminal output/log file).  The line in the copyright notice that's
overfull is one character than any others, so it goes beyond the right
margin.

In general, you can reformat the text, or use @smallexample, or if you
just want to live with the too-long lines (some of them look awfully
long, though), you can do
@finalout
and TeX will obligingly not print the black boxes.

Best,
k