[Node.js] - Unclear what "collection" is in Transactions example

const inventory = cluster.bucket('travel-sample').scope('inventory')try {

  await cluster.transactions().run(async (ctx) => {

    // Inserting a doc:

    await ctx.insert(collection, 'doc-a', {})    // Getting documents:

    const docA = await ctx.get(collection, 'doc-a')    // Replacing a doc:

    const docB = await ctx.get(collection, 'doc-b')

    const content = docB.content

    const newContent = {

      transactions: 'are awesome',

      ...content,

    }

    await ctx.replace(docB, newContent)    // Removing a doc:

    const docC = await ctx.get(collection, 'doc-c')

    await ctx.remove(docC)    // Performing a SELECT N1QL query against a scope:

    const qr = await ctx.query('SELECT * FROM hotel WHERE country = $1', {

      scope: inventory,

      parameters: ['United Kingdom'],

    })

    // ...qr.rows

    qr.rows    await ctx.query('UPDATE route SET airlineid = $1 WHERE airline = $2', {

      scope: inventory,

      parameters: ['airline_137', 'AF'],

    })  })

} catch (error) {

  if (error instanceof TransactionFailedError) {

    console.error('Transaction did not reach commit point', error)

  }  if (error instanceof TransactionCommitAmbiguousError) {

    console.error('Transaction possibly committed', error)

  }

}