fetchAccountData = async ({ customersTableName, userPoolId, adminsGroupName }) => {
  const [adminUserIds, accountsFromTable, usernamesByUserId] =
    await Promise.all([
      fetchAdminUserIds({ userPoolId, adminsGroupName }),
      fetchCustomersTableItems({ tableName: customersTableName }),
      fetchUsernamesByUserId({ userPoolId })
    ])

  let accounts = accountsFromTable
  accounts = insertIsAdmin({ accounts, adminUserIds })
  accounts = insertUsernames({ accounts, usernamesByUserId })

  const accountsAsTsv = accounts
    .map(account => accountDataAsTsv(account))
    .join('\n')
  return `${ACCOUNT_DATA_TSV_HEADER}\n${accountsAsTsv}\n`
}
TSV header for account account fields.