function getTatLen(x1, y1, x2, y2, x3, y3, x4, y4, ll) {
  if (ll < 0 || bezlen(x1, y1, x2, y2, x3, y3, x4, y4) < ll) {
    return;
  }
  var t = 1, step = t / 2, t2 = t - step, l, e = 0.01;
  l = bezlen(x1, y1, x2, y2, x3, y3, x4, y4, t2);
  while (Math.abs(l - ll) > e) {
    step /= 2;
    t2 += (l < ll ? 1 : -1) * step;
    l = bezlen(x1, y1, x2, y2, x3, y3, x4, y4, t2);
  }
  return t2;
}
Adds a value to the end of an array. Extends the length of
the array by one. Maps to Array.push().

@method append
@param {Array} array Array to append
@param {any} value to be added to the Array
@example
<div class = "norender"><code>
function setup() {

var myArray = new Array("Mango", "Apple", "Papaya")
print(myArray) // ["Mango", "Apple", "Papaya"]

append(myArray, "Peach")
print(myArray) // ["Mango", "Apple", "Papaya", "Peach"]

}
</div></code>