How to use the wikidata-sdk.isItemId function in wikidata-sdk

const validateReferenceArgs = (guid, property, reference) => {
  if (!_.isNonEmptyString(guid)) {
    throw error_.new('missing guid', 400, guid)
  }

  const [ entity, rest ] = guid.split('$')
  if (!wdk.isItemId(entity)) {
    throw error_.new('invalid guid', 400, guid)
  }

  if (!(_.isNonEmptyString(rest) && /[\w-]{36}/.test(rest))) {
    throw error_.new('invalid guid', 400, guid)
  }

  if (!_.isNonEmptyString(property)) {
    throw error_.new('missing property', 400, property)
  }

  validate.property(property)
  validate.referenceValue(property, reference)
}

const validateClaim = claim => {
  const [ P, Q ] = claim.split(':')
  if (!(isPropertyId(P))) throw new Error(`invalid claim property: ${P}`)
  if (Q) {
    const Qs = Q.split(',')
    for (let q of Qs) {
      if (!(isItemId(q))) throw new Error(`invalid claim value: ${q}`)
    }
  }
}