getValues = col => {

  if (Array.isArray(col)) {

    return col; // bounce back.

  } else if (col instanceof vis.DataSet) { // a dataset

    return col.get({ returnType: 'Array' });

  }

  const result = [];
  const keys = Object.keys(col);
  for (let i = keys.length; i--;) {
    result.push(col[keys[i]]);
  }

  return result;

}
Extract all the values from a collection. If `col` is an object,
only properties are considered that are its own and iterable.

@param {Collection} col
@return {Array} An array