builds a KeyVal from a Key and a series of key val args
builds a KeyVal from a Key and a series of key val args
longevity.exceptions.subdomain.root.NumPropValsException
if the number of key val args does not
match the number of properties in the key
longevity.exceptions.subdomain.root.PropValTypeException
if the type of the key val arg does not
not match the type of the corresponding property in the key