(a) to the extent that the agreed consideration has been performed or
that he acquires a security interest in or a lien on the instrument
otherwise than by legal process; or
(b) when he takes the instrument in payment of or as security for an
antecedent claim against any person whether or not the claim is due; or
(c) when he gives a negotiable instrument for it or makes an
irrevocable commitment to a third person.