✨ Added tutorial pattern

packages/tutorial/src/step3.js

@@ -0,0 +1,40 @@
+export default function(part) {
+  let { Point, points, Path, paths, measurements, options } = part.shorthand();
+
+  let tweak = 1;
+  let target = (measurements.headCircumference * options.neckRatio) / 4;
+  let delta = Infinity;
+  do {
+    points.right = new Point((tweak * measurements.headCircumference) / 10, 0);
+    points.bottom = new Point(0, (tweak * measurements.headCircumference) / 12);
+
+    points.rightCp1 = points.right.shift(
+      90,
+      points.bottom.dy(points.right) / 2
+    );
+    points.bottomCp2 = points.bottom.shift(
+      0,
+      points.bottom.dx(points.right) / 2
+    );
+
+    paths.neck = new Path()
+      .move(points.right)
+      .curve(points.rightCp1, points.bottomCp2, points.bottom);
+
+    delta = paths.neck.length() - target;
+    if (delta > 0) tweak = tweak * 0.99;
+    else tweak = tweak * 1.02;
+  } while (Math.abs(delta) > 1);
+
+  // Complete?
+  if (complete) {
+    if (sa) {
+    }
+
+    // Paperless?
+    if (paperless) {
+    }
+  }
+
+  return part;
+}