new_contents: from deform import Form
  
  class SchemaFormMixin(object):
      @classmethod
      def create_form(cls, *arg, **kw):
          schema_vars = {}
          form_vars = {}
  
          for sn in ['validator', 'preparer', 'after_bind']:
              if sn in kw:
                  schema_vars[sn] = kw[sn]
                  del kw[sn]
  
          for fv in ['action', 'buttons', 'method', 'formid', 'autocomplete',
                  'use_ajax', 'ajax_options']:
              if fv in kw:
                  form_vars[fv] = kw[fv]
                  del kw[fv]
  
          if 'validator' not in schema_vars and hasattr(cls, '__validator__'):
              schema_vars['validator'] = cls.__validator__
  
          if 'buttons' not in form_vars and hasattr(cls, '__buttons__'):
              form_vars['buttons'] = cls.__buttons__
          
          schema = cls(**schema_vars).bind(**kw)
          form = Form(schema, **form_vars)
  
          return (schema, form)
  
  
subject: Add a MixIn that makes it simpler to instantiate a deform