code: function reduceNonNa(array, initValue, func) {
    var result = initValue;
    for (var i = 0; i < array.length; i++) {
      var value = array[i];
      if (!isMissing(value)) {
        result = func(result, value);
      }
    }
    return result;
  }
docs: Performs a left-to-right reduce on 'array' using 'func' starting with 'initValue' while skipping over any missing values.  If there are no non-missing values then the result is simply 'initValue'.