How to use the @redux-saga/is.object function in @redux-saga/is

const validateFnDescriptor = (effectName, fnDescriptor) => {
  check(fnDescriptor, is.notUndef, `${effectName}: argument fn is undefined or null`)

  if (is.func(fnDescriptor)) {
    return
  }

  let context = null
  let fn

  if (is.array(fnDescriptor)) {
    ;[context, fn] = fnDescriptor
    check(fn, is.notUndef, `${effectName}: argument of type [context, fn] has undefined or null \`fn\``)
  } else if (is.object(fnDescriptor)) {
    ;({ context, fn } = fnDescriptor)
    check(fn, is.notUndef, `${effectName}: argument of type {context, fn} has undefined or null \`fn\``)
  } else {
    check(fnDescriptor, is.func, `${effectName}: argument fn is not function`)
    return
  }

  if (context && is.string(fn)) {
    check(context[fn], is.func, `${effectName}: context arguments has no such method - "${fn}"`)
    return
  }

  check(fn, is.func, `${effectName}: unpacked fn argument (from [context, fn] or {context, fn}) is not a function`)
}