src/index.js
function normalizeTolerance (t) {
  return t === Object(t) ? t : { down: t, up: t }
}
function normalizeTolerance (t) {
  return t === Object(t) ? t : { down: t, up: t }
}
function normalizeTolerance ( t ) { return t === Object ( t ) ? t : { down : t , up : t } }
Helper function for normalizing tolerance option to object format
Helper function for normalizing tolerance option to object format