Function d3_numeric

code/gmane/d3.v3.js:112–114

(x)

    return x === null ? NaN : +x;
  }
  function d3_numeric(x) {
    return !isNaN(x);
  }
  d3.sum = function(array, f) {
    var s = 0, n = array.length, a, i = -1;
    if (arguments.length === 1) {