A source$-$code optimiser is a program that can optimise programs at source$-$code level, i$.$e$.,$ a program O that reads a program P and outputs another program P$^\text{'},$ which is equivalent to P$,$ but may be faster. A source$-$code optimiser is like a compiler, except the source and target languages are the same. Hence, we can describe a sourcecode optimizer for C written in C with the diagram Assume that you additionally have the following components: $1.$ A compiler, written in ARM code, from C to ARM code. $2.$ A machine that can execute ARM code. $3.$ Some unspecified program P writen in C$.$ Now do the following: a$)$ Depict the above components as tombstone diagrams. b$)$ Show, using tombstone diagrams, the steps required to optimise P to P$^\text{'}$ and then execute P$^\text{'}.$