Revert "add stream::min_by method (#146)"

This reverts commit 7e3599a.

src/stream/mod.rs

@@ -27,7 +27,6 @@ pub use repeat::{repeat, Repeat};
 pub use stream::{Stream, Take};
 
 mod empty;
-mod min_by;
 mod once;
 mod repeat;
 mod stream;

src/stream/stream.rs

@@ -21,12 +21,10 @@
 //! # }) }
 //! ```
 
-use std::cmp::Ordering;
 use std::pin::Pin;
 
 use cfg_if::cfg_if;
 
-use super::min_by::MinBy;
 use crate::future::Future;
 use crate::task::{Context, Poll};
 use std::marker::PhantomData;
@@ -120,39 +118,6 @@ pub trait Stream {
         }
     }
 
-    /// Returns the element that gives the minimum value with respect to the
-    /// specified comparison function. If several elements are equally minimum,
-    /// the first element is returned. If the stream is empty, `None` is returned.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// # fn main() { async_std::task::block_on(async {
-    /// #
-    /// use std::collections::VecDeque;
-    /// use async_std::stream::Stream;
-    ///
-    /// let s: VecDeque<usize> = vec![1, 2, 3].into_iter().collect();
-    ///
-    /// let min = Stream::min_by(s.clone(), |x, y| x.cmp(y)).await;
-    /// assert_eq!(min, Some(1));
-    ///
-    /// let min = Stream::min_by(s, |x, y| y.cmp(x)).await;
-    /// assert_eq!(min, Some(3));
-    ///
-    /// let min = Stream::min_by(VecDeque::<usize>::new(), |x, y| x.cmp(y)).await;
-    /// assert_eq!(min, None);
-    /// #
-    /// # }) }
-    /// ```
-    fn min_by<F>(self, compare: F) -> MinBy<Self, F>
-    where
-        Self: Sized + Unpin,
-        F: FnMut(&Self::Item, &Self::Item) -> Ordering,
-    {
-        MinBy::new(self, compare)
-    }
-
     /// Tests if every element of the stream matches a predicate.
     ///
     /// `all()` takes a closure that returns `true` or `false`. It applies