'return action to create a bank statements. This button should be called only on journals with type ==\'bank\''

@api.multi
def create_bank_statement(self):

    self.bank_statements_source = 'manual'
    action = self.env.ref('account.action_bank_statement_tree').read()[0]
    action.update({'views': [[False, 'form']], 'context': (("{'default_journal_id':    " + str(self.id)) + '}')})
    return action
