Write a programme to plot the function $f(x)=xsin((9x+1))$ over the interval $-1,1$ using increments in $x$ of $($a$)0\mathrm{.}2,($b$)0\mathrm{.}1,$ and $($c$)0\mathrm{.}01.$ The programme should plot the three graphs in the same figure. Include the legend to specify which graph corresponds to which increment. $($Observe that the plots for cases $($a$)$ and $($b$)$ give totally the wrong picture of $f(x).)$