The error type for `try_reserve` methods.

A mutable iterator over the entries of a `HashMap`.

Error returned for the buffered data from `BufWriter::into_parts`, when the underlying writer has previously panicked. Contains the (possibly partly written) buffered data.

An iterator over `u8` values of a reader.

An iterator over the contents of an instance of `BufRead` split on a particular byte.

An iterator that yields a single element of type `A` by applying the provided closure `F: FnOnce() -> A`.

The error type for operations on the `PATH` variable. Possibly returned from `env::join_paths()`.

`Request` supports generic, type-driven access to data. Its use is currently restricted to the standard library in cases where trait authors wish to allow trait implementors to share generic information across trait boundaries. The motivating and prototypical use case is `core::error::Error` which would otherwise require a method per concrete type (eg. `std::backtrace::Backtrace` instance that implementors want to expose to users).

Creates a future which never resolves, representing a computation that never finishes.

Options and flags which can be used to configure how a file is opened.