In order to print the book loan report with report_py3o, you need to do the following:

1. In my_module/data, add a file called py3o_server.xml with the following content:

<?xml version="1.0" encoding="utf-8"?>
<odoo>
  <record id="local_py3o_server" model="py3o.server">
    <field name="url">http://localhost:8765/form</field>
  </record>
</odoo>

2. In my_module/reports, add a file called book_loan_report.xml with the following content:

<?xml version="1.0" encoding="utf-8"?>
<odoo>
  <record id="report_book_loans_py3o" model="ir.actions.report.xml">
    <field name="name">Book Loans</field>
    <field name="model">library.member</field>
    <field name="report_name">library.member.loans</field>
    <field name="report_type">py3o</field>
    <field name="py3o_filetype">pdf</field>
    <field name="py3o_server_id" ref="local_py3o_server"/>
    <field name="module">my_module</field>
    <field 
    name="py3o_template_fallback">reports/book_loans.odt</field>
  </record>

</odoo>

3. Add both files to the manifest of the addon, and declare a dependency on report_py3o:

{
    'name': 'Chapter 14 code the py3o recipe',
    'depends': ['mail', 'report_py3o'],
    'data': [
        'data/py3o_server.xml',
        'reports/book_loan_report.xml'
        # ...
    ],
}

4. Create an empty LibreOffice ODT document and save it in reports/book_loans.odt
5. Place the cursor at the beginning of the document, and choose Insert > Hyperlink... in the menu
6. In the dialog, set the following as shown in the screen capture below:
   • Target: py3o://for="member in objects"
   • Text: for="member in objects"

7. After the hyperlink, set the format as Title, and type Book loans for
8. With the cursor after "for", choose Insert > Field > More Fields... (Ctrl+F2) in the menu
9.  In the dialog, choose the Variables tab:
   • Set the Type to User Field
   • Set Name to py3o.member.name
   • Set Value to Member Name
   • Click on the Insert button:

10. Insert a table with two columns and four rows
11. In the first row, type Book title and Expected return date
12. In the second row, insert a hyperlink as you did in step 6. The Target is py3o://for="loan in member.loan_ids" and the Text is for="loan in member.loan_ids"
13. In the third row, insert these to the user fields as you did in step 9:
    • In the first column, the Name is py3o.loan.book_id.name and the Value is Book Title
    • In the second column, the Name is py3o.loan.expected_return_date and the Value is Expected Return Date

14. In the last row, insert a hyperlink as you did in step 12. The Target is py3o:///for and the text is /for
15. After the table, insert a hyperlink as you did in step 14 with the same Target and Text

Here's what your document should look like:

To test your report, install your module. Display a library member and select Print > Book Loans.