Accessor and Mutator Methods in Dexterity

Question

I'm beginner user of dexterity (about 2 days now). I'm trying to migrate my old content type to dextertiy content in process of migrating website.

Schema defination in classic archetype is like

TextField('script',
          searchable=0,
          mutator="write",
          accessor="__call__",
          edit_accessor="document_src",
          widget=TextAreaWidget(label="Page Template script",rows=40,cols=40),

How can I redefine in dexterity ? I'm upgrading from Plone 252 to Plone 412.

Regards,