rhat(fit = NULL, less = NULL)hBayesDM'less' is specified, then rhat(fit, less) will return TRUE if all Rhat values are
less than or equal to 'less'. If any values are greater than 'less', rhat(fit, less) will
return FALSE. If 'less' is left unspecified (NULL), rhat(fit) will return a data.frame object
containing all Rhat values.