Exercise $9.$ The Python function Sharpe$\_$Ratio uses a "helper" function data$\_$func to calculate the ${}_a,{}_b,R_a,R_b$ and $$ from a data set of $20$ stocks. This data is then used by the sharpe$\_$Ratio function to calculate $x$ and $y(x_{-}$optimal and $y_{-}$optimal$)$ and return the optimal Sharpe Ratio s$\_$max. Finish Sharpe$\_$Ratio by filling in the missing line of code below. Hint: How did you find the amount to invest in stock B in the previous exercise?

$[]$ from math import sqrt

def Sharpe$\_$Ratio $($stock$\_$A$\_$ticker, stock$\_$B$\_$ticker, R$\_$f$)$ :

$(a,b,s,t,p)=$ data$\_$func $($stock$\_$A$\_$ticker, stock$\_$B$\_$ticker$)$

$r=R_{-}f$

y$\_$optimal $=$ # Finish this line.

S$\_$max $=\frac{a**x_o\text{p}\text{t}\text{i}\text{m}\text{a}\text{l}+b**y_o\text{p}\text{t}\text{i}\text{m}\text{a}\text{l}-r}{\sqrt[\phantom{2}]{s****2**x_o\text{p}\text{t}\text{i}\text{m}\text{a}\text{l}*****2+t****2**y_o\text{p}\text{t}\text{i}\text{m}\text{a}\text{l}*****2+p**s**t**x_o\text{p}\text{t}\text{i}\text{m}\text{a}\text{l}**y_o\text{p}\text{t}\text{i}\text{m}\text{a}\text{l}}}$

print$($f$"$The maximum possible Sharpe Ratio for these two stocks is $($round$($S$\_$max, $4)\}.$ The unrounded Sharpe Ratio is$")$

return $S_{-}$max