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use futures_core::Stream;

pub(crate) mod array;
pub(crate) mod tuple;
pub(crate) mod vec;

/// Combines multiple streams into a single stream of all their outputs.
///
/// Items are yielded as soon as they're received, and the stream continues
/// yield until both streams have been exhausted. The output ordering
/// between streams is not guaranteed.
///
/// # Examples
///
/// ```
/// use merge_streams::MergeStreams;
/// use futures_lite::prelude::*;
/// use futures_lite::{future::block_on, stream};
///
/// fn main() {
///     block_on(async {
///         let a = stream::once(1);
///         let b = stream::once(2);
///         let c = stream::once(3);
///         let mut s = [a, b, c].merge();
///
///         let mut buf = vec![];
///         s.for_each(|n| buf.push(n)).await;
///         buf.sort_unstable();
///         assert_eq!(&buf, &[1, 2, 3]);
///     })
/// }
/// ```
pub trait MergeStreams {
    /// The resulting output type.
    type Item;

    /// The stream type.
    type Stream: Stream<Item = Self::Item>;

    /// Combine multiple streams into a single stream.
    fn merge(self) -> Self::Stream;
}