Hi, 

in COA, Let suppose you want to return account.code + ' ' + account.name rather than default name so you will override name_get method as below:

@api.multi
@api.depends('name', 'code')
def name_get(self):
    result = []
    for account in self:
        name = account.code + ' ' + account.name
        result.append((account.id, name))
    return result