Conversation so far:
What were some of Cosmo Kramer's pseudonyms?
H.E.
Pennypacker in.
Which episode did he use this name in?
"The Puerto Rican Day".
What happened in this episode?
", Kramer poses as a prospective buyer interested in an elegant apartment.
Does he end up getting the apartment?
CANNOTANSWER.
What other names does he use?
Dr.
Martin van Nostrand.
Which episode does he use this name in?
"The Package".

Question: What is the main plot of that episode?
Self-contained rewrite: What is the main plot of The Package episode?