Question: Use the macroinstruction searchright in Exercise to create a Turing machine program that replaces the symbol immediately to the left of the leftmost a by a blank. If the input contains no a, replace the rightmost nonblank symbol by a b.
Exercise: Give an implementation of the macroinstruction search right (a, qi, qj), which indicates that the machine is to search its tape to the right of the current position for the first occurrence of the symbol a. If an a is encountered before a blank, the machine is to go into state qi, otherwise it is to go into state qj.