code: function triangle () {
    let a = arguments
    if (a[0] && a[0].length) a = a[0]
    return fromPoints(a)
  }
docs: FIXME: errr this is kinda just a special case of a polygon , why do we need it ? Construct a triangle
  @returns {CAG} new triangle
  
  @example
  let triangle = trangle({
  length: 10
  })