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function create(tag, attr = {}, children = []) {
  children = Array.isArray(children) ? children : [children];
  const elm = document.createElement(tag);
  for (let a in attr) {
    if (a.startsWith('on')) {
      elm.addEventListener(a.slice(2).toLowerCase(), attr[a])
    } else {
      if (attr[a]) elm.setAttribute(a, attr[a]);
    }
  }

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function* each(arr) {
  let i;
  for (i = 0; i < arr.length; i++) yield arr[i];
}

export function* traverse (arr) {
  let queue = [each(arr)];
  let seen = new WeakSet();

  while (queue.length) {

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function createList() {
  var next = 'prev'
    , prev = 'next'
    , length = 0
    , head
    , tail
    , arr
    , n;

  return {

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// SOLUTION 1

const getBlobBoundingBox1 = (blobString) => {
  blobString = blobString.trim()

  const width = (/\s/.exec(blobString) || {}).index
  const one = /1/g

  blobString = blobString.replace(/\s+/g, '')

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// -------------------------------------------------------------------------------------------------------
// Once (from source of async)
// @see https://github.com/caolan/async/blob/f5d86b80b986c8cad88a224a6f8b3ec154839490/lib/internal/once.js
// -------------------------------------------------------------------------------------------------------

function once(fn) {
    return function () {
        if (fn === null) return;
        var callFn = fn;
        fn = null;

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// A compressor for anagram puzzle data
// because we know all the solutions to anagram puzzles
// have a very small number of characters, we can compress
// the data more strategically
//
// given a list of letters, this creates an encode and decode function
//
// for example
// given the letters:
//    'NCEHITK'

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// logs this pattern
//         * 
//        * * 
//       *   * 
//      * * * * 
//     *       * 
//    * *     * * 
//   *   *   *   * 
//  * * * * * * * * 

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// not really about performance
// but fun to make it one line
// this discussion looked interesting re estimating
// https://stackoverflow.com/questions/3693514/very-fast-3d-distance-check

const distance = (a, b) => Math.sqrt(a.reduce((total, _, i) => total + Math.pow(b[i] - a[i], 2), 0))

const _2d_ = distance([1, 2], [0, 4])
const _3d_ = distance([1, 2, 3], [0, 4, 5])

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// walk around the edges of a grid
// and work toward the center
// Begin going right.
// When you are at an edge or a filled square, turn right.
const spiral = (w, h, fn) => {
  // a map where keys are visited indexes
  const visited = {}

  // translations represent increments for: right -> down -> left -> up
  const translations = [1, w, -1, -w]

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// >>> is perf hack for flooring positive numbers
const rand = (min, max) => ((Math.random() * (max - min + 1)) >>> 0) + min
const randItem = (arr) => arr[rand(0, arr.length - 1)]

const isDef = v => typeof v !== 'undefined'
const isUndef = v => typeof v === 'undefined'

const directions = [
  (w, h, x, y, i) => y > 0 ? i - w : undefined,
  (w, h, x, y, i) => y < h - 1 ? i + w : undefined,