For problems $4-10,$ give the BNF grammar for the

following problems. $($Yes$,$ they are out of order from what the book does. There's a reason that I have them listed in this order, however.$)$

$4.$ Chapter $2.$ Exercise $1.$a$.$

The set of all strings consisting of zero or more as$.$

$5.$ Chapter $2.$ Exercise $1.$c$.$

The set of all strings consisting of one or more as$.$

$6.$ Chapter $2.$ Exercise $1.$i$.$

The set of all strings consisting of one or more as$,$ with a comma between each a and the next. $($There should be no comma before the first or after the last.$)$

$7.$ Chapter $2.$ Exercise $1.$d$.$

The set of all strings consisting of one or more digits. $($Each digit is one of the characters $0$ through $9.)$

$8.$ Chapter $2.$ Exercise $1.$j$.$

The set of all strings consisting of an open bracket $($the symbol $[)$ followed by a list of one or more digits separated by commas, followed by a closing bracket $($the symbol $]).$

$9.$ Chapter $2.$ Exercise $1.$b$.$

The set of all strings consisting of an uppercase letter followed by zero or more additional characters, each of which is either an uppercase letter or one of the digits $0$ through $9.$

$10.$ Chapter $2.$ Exercise $1.$h$.$

The set of all strings consisting of the keyword begin, followed by one or more statements with a semicolon after each one, followed by the keyword end. Use the non$-$terminal