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//! Defines the `Depth` type and its related constants.
/// Search depth in half-moves.
///
/// A value of this type can be interpreted in two ways:
///
/// * **Remaining search depth.**
///
/// The remaining search depth tells how many half-moves should be
/// added to the current line of play before a leaf node is
/// reached. Usually, searches are started with some positive
/// number as their remaining search depth. This number is
/// decremented when a move is tried, and the search routine is
/// called recursively. When the remaining depth becomes zero (or
/// less), a leaf node has been reached and an evaluation is
/// assigned to it. Sometimes depth reductions are applied for less
/// interesting moves. This means that the remaining search depth
/// is decreased by more than one. Thus, if such reductions are
/// applied near leaf nodes, the remaining search depth may become
/// negative.
///
/// * **Completed search depth.**
///
/// The completed search depth tells the depth in half-moves to
/// which a position has been analyzed. Negative values are
/// possible, meaning that a search with a negative remaining
/// search depth has been executed for the position.
///
/// # Limits:
///
/// * `DEPTH_MAX` is the maximum allowed search depth in half-moves (a
/// positive number).
///
/// * `DEPTH_MIN` is the minimum allowed search depth in half-moves (a
/// negative number).
pub type Depth = i8;
pub const DEPTH_MIN: i8 = -32;
pub const DEPTH_MAX: i8 = 95;