@FUNCTION=OPT_BINOMIAL
@SYNTAX=OPT_BINOMIAL(amer_euro_flag,call_put_flag,num_time_steps, spot, strike, time, rate, volatility, cost_of_carry)
@DESCRIPTION=OPT_ models the theoretical price of either an American or European style option using a binomial tree.
@amer_euro_flag is either 'a' or 'e' to indicate whether the option being valued is an American or European style option respectively.
@call_put_flag is 'c' or 'p' to indicate whether the option is a call or a put.
@num_time_steps is the number of time steps used in the valuation, a greater number of time steps yields greater accuracy however is slower to calculate.
@spot is the spot price of the underlying asset.
@strike is the strike price at which the option is struck.
@time is the initial maturity of the option in years.
@rate is the annualized risk-free rate of interest.
@volatility is the annualized volatility in price of the underlying asset.
@cost_of_carry is the leakage in value of the underlying asset.
@EXAMPLES=
@SEEALSO=OPT_BS, OPT_BS_DELTA, OPT_BS_RHO, OPT_BS_THETA, OPT_BS_GAMMA
