1. Make it as easy to modify the composition of a portfolio, as it is to modify the value of a parameter. Treat the portfolio composition as an optimizable variable.
2. Make it easy to systematically withdraw cash from the account using some user-specified algorithm. Handle the common situations of income taxes, management fees, and profit incentive fees.
3. Provide primitive builtins which return (A) # of trading days till end of this calendar month; (B) # of trading days till First Notice Day; (C) # of trading days till Contract Expiration.