5. Consider the following language for arithmetic expressions that contains a nullary (arity 0) op- erator zero, a unary (arity 1) operator succ (successor), a unary operator pred (predecessor), a unary operator iszero (is-zero check), a ternary (arity 3) infix operator if-then-else, a nullary operator true, and a nullary operator false. . Define a BNF for this language. Your BNF should contain a single rule (of the form Ihs ::= rhs1 | . . . | rhon). . Indicate whether some expressions can be ambiguous. . Let e be an arithmetic expression. Using this grammar, write down another expression that returns zero if e is zero, and otherwise returns e's predecessor. In addition, write down the