'Convert the ``values`` dictionary into cached values.
:param update: whether the conversion is made for updating ``self``;
this is necessary for interpreting the commands of *2many fields
:param validate: whether values must be checked'

def _convert_to_cache(self, values, update=False, validate=True):

    fields = self._fields
    target = (self if update else self.browse([], self._prefetch))
    return {name: fields[name].convert_to_cache(value, target, validate=validate) for (name, value) in values.iteritems() if (name in fields)}
