$ cargo run
   Compiling collections v0.1.0 (file:///projects/collections)
error[E0277]: the type `std::string::String` cannot be indexed by `{integer}`
 --> src/main.rs:3:13
  |
3 |     let h = s1[0];
  |             ^^^^^ `std::string::String` cannot be indexed by `{integer}`
  |
  = help: the trait `std::ops::Index<{integer}>` is not implemented for `std::string::String`

error: aborting due to previous error

For more information about this error, try `rustc --explain E0277`.
error: could not compile `collections`.

To learn more, run the command again with --verbose.
