function validSwipe(coords) {
        // Check that it's within the coordinates.
        // Absolute vertical distance must be within tolerances.
        // Horizontal distance, we take the current X - the starting X.
        // This is negative for leftward swipes and positive for rightward swipes.
        // After multiplying by the direction (-1 for left, +1 for right), legal swipes
        // (ie. same direction as the directive wants) will have a positive delta and
        // illegal ones a negative delta.
        // Therefore this delta must be positive, and larger than the minimum.
        if (!startCoords) return false;
        var deltaY = Math.abs(coords.y - startCoords.y);
        var deltaX = (coords.x - startCoords.x) * direction;
        return valid && // Short circuit for already-invalidated swipes.
            deltaY < MAX_VERTICAL_DISTANCE &&
            deltaX > 0 &&
            deltaX > MIN_HORIZONTAL_DISTANCE &&
            deltaY / deltaX < MAX_VERTICAL_RATIO;
      }
@ngdoc directive
@name ngSwipeRight

@description
Specify custom behavior when an element is swiped to the right on a touchscreen device.
A rightward swipe is a quick, left-to-right slide of the finger.
Though ngSwipeRight is designed for touch-based devices, it will work with a mouse click and drag
too.

Requires the {@link ngTouch `ngTouch`} module to be installed.

@element ANY
@param {expression} ngSwipeRight {@link guide/expression Expression} to evaluate
upon right swipe. (Event object is available as `$event`)

@example
    <example module="ngSwipeRightExample" deps="angular-touch.js">
      <file name="index.html">
        <div ng-show="!showActions" ng-swipe-left="showActions = true">
          Some list content, like an email in the inbox
        </div>
        <div ng-show="showActions" ng-swipe-right="showActions = false">
          <button ng-click="reply()">Reply</button>
          <button ng-click="delete()">Delete</button>
        </div>
      </file>
      <file name="script.js">
        angular.module('ngSwipeRightExample', ['ngTouch']);
      </file>
    </example>