Function compose

d3-3.2.8/d3.js:3055–3057

(x, y)

  }
  function d3_geo_compose(a, b) {
    function compose(x, y) {
      return x = a(x, y), b(x[0], x[1]);
    }
    if (a.invert && b.invert) compose.invert = function(x, y) {
      return x = b.invert(x, y), x && a.invert(x[0], x[1]);
    };