docs: function fargs (a, o) {
    o = o || 0;
    var length = a.length - o;
  
    // Handle most common lengths manually.
    // This is where the speed comes in.
    if (length <= 0) return [];
    switch (length) {
      case 1: return [a[o]];
      case 2: return [a[o++], a[o++]];
      case 3: return [a[o++], a[o++], a[o++]];
      case 4: return [a[o++], a[o++], a[o++], a[o++]];
      case 5: return [a[o++], a[o++], a[o++], a[o++], a[o++]];
      case 6: return [a[o++], a[o++], a[o++], a[o++], a[o++], a[o++]];
    }
  
    // Fall back on a fast slice.
    var result = new Array(length);
    for (var i = 0; i < length; i++) result[i] = a[o + i];
    return result;
  }