I can change my Work Order sequence in my model fairly easy with this description link.

https://odootricks.tips/about/automated-actions/set-sequence-numbers-for-sales-orders/

i.e. in UI using developer mode.


When I try to code it .....

 This part of my code (creating a new sequence) works fine:

    <!-- New sequence for work.order -->
    <record id="seq_work_order" model="ir.sequence">
        <field name="name">Work Order</field>
        <field name="code">work.order</field>
        <field name="prefix">WO</field>
        <field name="padding">3</field>
        <field name="company_id" eval="False"/>
    </record>

Whereas the part where I create the  automated action:

       <!-- Automated action for work.order -->
    <record model="ir.actions.server" id="work_order_sequence">
        <field name="name">Work Order Sequence Action</field>
        <field name="model_id" ref="model_sale_order"/>
        <field name="state">code</field>
        <field name="code">
            for record in records:
            if record.order_type == "Workorder":
            ref = env['ir.sequence'].next_by_code('work.order')
            record['name'] = ref
        </field>
    </record>

Odoo creates the following  error:

odoo.tools.convert.ParseError: "IndentationError : expected an indented block at line 3
            ref = env['ir.sequence'].next_by_code('work.order')

None" while parsing /opt/odoo12/odoo/custom-addons/yachtservice/views/work_order_view.xml:60, near
<record model="ir.actions.server" id="work_order_sequence">
        <field name="name">Work Order Sequence Action</field>
        <field name="model_id" ref="model_sale_order"/>
        <field name="state">code</field>
        <field name="code">
            for record in records:
            if record.order_type == "Workorder":
            ref = env['ir.sequence'].next_by_code('work.order')
            record['name'] = ref
        </field>
    </record>