Please read the following table in HTML format from a webpage and then answer the question in detail according to the table. Each table cell is defined by a <td> and a </td> tag. Each table row starts with a <tr> and ends with a </tr> tag. 'rowspan=m' and 'colspan=n' represents a cell spaning over 'm' rows and 'n' columns.

Webpage title:
Lowestoft railway station
Table title:
Services
Table:
<table id='hittask' contenteditable='False'>
<tr> <th colspan=1 rowspan=1 > Operator </th><th colspan=1 rowspan=1 > Route </th><th colspan=1 rowspan=1 > Rolling stock </th><th colspan=1 rowspan=1 > Typical frequency </th></tr>
<tr> <td colspan=1 rowspan=1 > Abellio Greater Anglia </td><td colspan=1 rowspan=1 > Lowestoft - Oulton Broad North - Somerleyton - Haddiscoe - Reedham - Cantley - Brundall - Norwich </td><td class="highlighted"  colspan=1 rowspan=1 > Class 153, Class 156, Class 170 </td><td colspan=1 rowspan=1 > 1x per hour in each direction </td></tr>
<tr> <td colspan=1 rowspan=1 > Abellio Greater Anglia </td><td colspan=1 rowspan=1 > Lowestoft - Oulton Broad South - Beccles - Brampton (on request) - Halesworth - Darsham - Saxmundham - Wickham Market - Melton - Woodbridge - Ipswich </td><td class="highlighted"  colspan=1 rowspan=1 > Class 153, Class 156, Class 170 </td><td colspan=1 rowspan=1 > 1x per hour in each direction </td></tr>
</table>
Question:
By which classes are the Lowestoft railway station services are formed ?
Answer:
The Lowestoft railway station services are typically formed by Class 153, 156 or 170.