Remove `example` fn

[MrMaxie]

Is there any reason for there to be an example function in the code? From my observations, the code for this function is incorrect and ends up with a build problem (missing imports?), but it is also useless(?).

During the build I get the following error:

error[E0412]: cannot find type `AsyncStream` in crate `async_stream`
   --> ***\.cargo\registry\src\index.crates.io-6f17d22bba15001f\reql-0.11.1\src\lib.rs:745:52
    |
745 |     Q: FnOnce(r, &'a mut Session) -> async_stream::AsyncStream<(), F>,
    |                                                    ^^^^^^^^^^^ not found in `async_stream`
    |
help: consider importing this struct
    |
71  + use async_stream::__private::AsyncStream;
    |
help: if you import `AsyncStream`, refer to it directly
    |
745 -     Q: FnOnce(r, &'a mut Session) -> async_stream::AsyncStream<(), F>,
745 +     Q: FnOnce(r, &'a mut Session) -> AsyncStream<(), F>,
    |

For more information about this error, try `rustc --explain E0412`.
error: could not compile `reql` (lib) due to previous error

Fork and remove this function solves the problem completely, everything works correctly. The question I have is whether actually this function can be removed? Does its existence have no other purpose?