gistfile1.txt

   Compiling mdbook v0.3.5
error[E0658]: use of unstable library feature 'range_contains': recently added as per RFC (see issue #32311)
  --> /root/.cargo/registry/src/github.com-1ecc6299db9ec823/mdbook-0.3.5/src/utils/string.rs:66:19
   |
66 |         if !range.contains(&index) {
   |                   ^^^^^^^^

error: aborting due to previous error

For more information about this error, try `rustc --explain E0658`.
error: failed to compile `mdbook v0.3.5`, intermediate artifacts can be found at `/tmp/cargo-installLSGYGA`

Caused by:
  Could not compile `mdbook`.

To learn more, run the command again with --verbose.
The command '/bin/sh -c cargo install mdbook --vers "^0.3.4"' returned a non-zero code: 101