function isTimestamp (field, value) {
  return typeof value === 'number' &&
    value > YEAR_2000 &&
    isFinite(value) &&
    Math.floor(value) === value &&
    !isNaN(new Date(value).valueOf())
}
Test whether some field contains a timestamp in milliseconds after the year 2000.
@param {string} field
@param {number} value
@return {boolean}