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+Anyhow&ensp;¯\\\_(°ペ)\_/¯
+==========================
+
+[<img alt="github" src="https://img.shields.io/badge/github-dtolnay/anyhow-8da0cb?style=for-the-badge&labelColor=555555&logo=github" height="20">](https://github.com/dtolnay/anyhow)
+[<img alt="crates.io" src="https://img.shields.io/crates/v/anyhow.svg?style=for-the-badge&color=fc8d62&logo=rust" height="20">](https://crates.io/crates/anyhow)
+[<img alt="docs.rs" src="https://img.shields.io/badge/docs.rs-anyhow-66c2a5?style=for-the-badge&labelColor=555555&logo=docs.rs" height="20">](https://docs.rs/anyhow)
+[<img alt="build status" src="https://img.shields.io/github/actions/workflow/status/dtolnay/anyhow/ci.yml?branch=master&style=for-the-badge" height="20">](https://github.com/dtolnay/anyhow/actions?query=branch%3Amaster)
+
+This library provides [`anyhow::Error`][Error], a trait object based error type
+for easy idiomatic error handling in Rust applications.
+
+[Error]: https://docs.rs/anyhow/1.0/anyhow/struct.Error.html
+
+```toml
+[dependencies]
+anyhow = "1.0"
+```
+
+*Compiler support: requires rustc 1.39+*
+
+<br>
+
+## Details
+
+- Use `Result<T, anyhow::Error>`, or equivalently `anyhow::Result<T>`, as the
+  return type of any fallible function.
+
+  Within the function, use `?` to easily propagate any error that implements the
+  `std::error::Error` trait.
+
+  ```rust
+  use anyhow::Result;
+
+  fn get_cluster_info() -> Result<ClusterMap> {
+      let config = std::fs::read_to_string("cluster.json")?;
+      let map: ClusterMap = serde_json::from_str(&config)?;
+      Ok(map)
+  }
+  ```
+
+- Attach context to help the person troubleshooting the error understand where
+  things went wrong. A low-level error like "No such file or directory" can be
+  annoying to debug without more context about what higher level step the
+  application was in the middle of.
+
+  ```rust
+  use anyhow::{Context, Result};
+
+  fn main() -> Result<()> {
+      ...
+      it.detach().context("Failed to detach the important thing")?;
+
+      let content = std::fs::read(path)
+          .with_context(|| format!("Failed to read instrs from {}", path))?;
+      ...
+  }
+  ```
+
+  ```console
+  Error: Failed to read instrs from ./path/to/instrs.json
+
+  Caused by:
+      No such file or directory (os error 2)
+  ```
+
+- Downcasting is supported and can be by value, by shared reference, or by
+  mutable reference as needed.
+
+  ```rust
+  // If the error was caused by redaction, then return a
+  // tombstone instead of the content.
+  match root_cause.downcast_ref::<DataStoreError>() {
+      Some(DataStoreError::Censored(_)) => Ok(Poll::Ready(REDACTED_CONTENT)),
+      None => Err(error),
+  }
+  ```
+
+- If using the nightly channel, or stable with `features = ["backtrace"]`, a
+  backtrace is captured and printed with the error if the underlying error type
+  does not already provide its own. In order to see backtraces, they must be
+  enabled through the environment variables described in [`std::backtrace`]:
+
+  - If you want panics and errors to both have backtraces, set
+    `RUST_BACKTRACE=1`;
+  - If you want only errors to have backtraces, set `RUST_LIB_BACKTRACE=1`;
+  - If you want only panics to have backtraces, set `RUST_BACKTRACE=1` and
+    `RUST_LIB_BACKTRACE=0`.
+
+  The tracking issue for this feature is [rust-lang/rust#53487].
+
+  [`std::backtrace`]: https://doc.rust-lang.org/std/backtrace/index.html#environment-variables
+  [rust-lang/rust#53487]: https://github.com/rust-lang/rust/issues/53487
+
+- Anyhow works with any error type that has an impl of `std::error::Error`,
+  including ones defined in your crate. We do not bundle a `derive(Error)` macro
+  but you can write the impls yourself or use a standalone macro like
+  [thiserror].
+
+  ```rust
+  use thiserror::Error;
+
+  #[derive(Error, Debug)]
+  pub enum FormatError {
+      #[error("Invalid header (expected {expected:?}, got {found:?})")]
+      InvalidHeader {
+          expected: String,
+          found: String,
+      },
+      #[error("Missing attribute: {0}")]
+      MissingAttribute(String),
+  }
+  ```
+
+- One-off error messages can be constructed using the `anyhow!` macro, which
+  supports string interpolation and produces an `anyhow::Error`.
+
+  ```rust
+  return Err(anyhow!("Missing attribute: {}", missing));
+  ```
+
+  A `bail!` macro is provided as a shorthand for the same early return.
+
+  ```rust
+  bail!("Missing attribute: {}", missing);
+  ```
+
+<br>
+
+## No-std support
+
+In no_std mode, the same API is almost all available and works the same way. To
+depend on Anyhow in no_std mode, disable our default enabled "std" feature in
+Cargo.toml. A global allocator is required.
+
+```toml
+[dependencies]
+anyhow = { version = "1.0", default-features = false }
+```
+
+Since the `?`-based error conversions would normally rely on the
+`std::error::Error` trait which is only available through std, no_std mode will
+require an explicit `.map_err(Error::msg)` when working with a non-Anyhow error
+type inside a function that returns Anyhow's error type.
+
+<br>
+
+## Comparison to failure
+
+The `anyhow::Error` type works something like `failure::Error`, but unlike
+failure ours is built around the standard library's `std::error::Error` trait
+rather than a separate trait `failure::Fail`. The standard library has adopted
+the necessary improvements for this to be possible as part of [RFC 2504].
+
+[RFC 2504]: https://github.com/rust-lang/rfcs/blob/master/text/2504-fix-error.md
+
+<br>
+
+## Comparison to thiserror
+
+Use Anyhow if you don't care what error type your functions return, you just
+want it to be easy. This is common in application code. Use [thiserror] if you
+are a library that wants to design your own dedicated error type(s) so that on
+failures the caller gets exactly the information that you choose.
+
+[thiserror]: https://github.com/dtolnay/thiserror
+
+<br>
+
+#### License
+
+<sup>
+Licensed under either of <a href="LICENSE-APACHE">Apache License, Version
+2.0</a> or <a href="LICENSE-MIT">MIT license</a> at your option.
+</sup>
+
+<br>
+
+<sub>
+Unless you explicitly state otherwise, any contribution intentionally submitted
+for inclusion in this crate by you, as defined in the Apache-2.0 license, shall
+be dual licensed as above, without any additional terms or conditions.
+</sub>