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/// Array zip macro: lock step function application across several arrays and
/// producers.
///
/// This is a shorthand for [`Zip`](struct.Zip.html).
///
/// This example:
///
/// ```rust,ignore
/// azip!(mut a, b, c in { *a = b + c })
/// ```
///
/// Is equivalent to:
///
/// ```rust,ignore
/// Zip::from(&mut a).and(&b).and(&c).apply(|a, &b, &c| {
/// *a = b + c;
/// });
///
/// ```
///
/// Explanation of the shorthand for captures:
///
/// + `mut a`: the producer is `&mut a` and the variable pattern is `mut a`.
/// + `b`: the producer is `&b` and the variable pattern is `&b` (same for `c`).
///
/// The syntax is `azip!(` *[* `index` *pattern* `,`*] capture [*`,` *capture [*`,` *...] ]* `in {` *expression* `})`
/// where the captures are a sequence of pattern-like items that indicate which
/// arrays are used for the zip. The *expression* is evaluated elementwise,
/// with the value of an element from each producer in their respective variable.
///
/// More capture rules:
///
/// + `ref c`: the producer is `&c` and the variable pattern is `c`.
/// + `mut a (expr)`: the producer is `expr` and the variable pattern is `mut a`.
/// + `b (expr)`: the producer is `expr` and the variable pattern is `&b`.
/// + `ref c (expr)`: the producer is `expr` and the variable pattern is `c`.
///
/// Special rule:
///
/// + `index i`: Use `Zip::indexed` instead. `i` is a pattern -- it can be
/// a single variable name or something else that pattern matches the index.
/// This rule must be the first if it is used, and it must be followed by
/// at least one other rule.
///
/// **Panics** if any of the arrays are not of the same shape.
///
/// ## Examples
///
/// ```rust
/// #[macro_use(azip)]
/// extern crate ndarray;
///
/// use ndarray::Array2;
///
/// type M = Array2<f32>;
///
/// fn main() {
/// let mut a = M::zeros((16, 16));
/// let mut b = M::zeros(a.dim());
/// let mut c = M::zeros(a.dim());
///
/// // set up values in b, c
/// b.fill(1.);
/// for ((i, j), elt) in c.indexed_iter_mut() {
/// *elt = (i + 10 * j) as f32;
/// }
///
/// // Compute a simple ternary operation:
/// // elementwise addition of b and c, stored in a
///
/// azip!(mut a, b, c in { *a = b + c });
///
/// assert_eq!(a, &b + &c);
///
/// // Example of azip!() with index
///
/// azip!(index (i, j), b, c in {
/// a[[i, j]] = b - c;
/// });
///
/// assert_eq!(a, &b - &c);
/// }
/// ```
) => ;
// parsing stack: [expressions] [patterns] (one per operand)
// index uses empty [] -- must be first
=> ;
=> ;
=> ;
=> ;
=> ;
=> ;
=> ;
=> ;
=> ;
=>
}