var common = typeof window !== 'undefined' ? window : exports

common.colors20 = [
  [255, 106, 152], [255, 98, 188], [250, 98, 219], [231, 107, 243],
  [199, 124, 255], [149, 144, 255], [53, 162, 255], [0, 176, 246],
  [0, 186, 224], [0, 191, 196], [0, 193, 163], [0, 191, 125],
  [0, 187, 78], [57, 182, 0], [124, 174, 0], [163, 165, 0],
  [192, 155, 0], [216, 144, 0], [234, 131, 49], [248, 118, 109],
  [255, 106, 152]
]

common.interpolate = function (a, b, n) {
  if (!a) a = [0, 0, 0, 0]
  if (!b) b = [0, 0, 0, 0]
  var m = 1 - n
  return [
    a[0] * m + b[0] * n,
    a[1] * m + b[1] * n,
    a[2] * m + b[2] * n,
    a[3] * m + b[3] * n,
  ]
}