What is the regular expression for a grade in the range $0\mathrm{.}74\mathrm{.}0$ That is$,$ it must match:

a$.$ The numeral $0,$ followed by a period, followed by any numeral in the set $7,8,9$

b$.$ Or the numeral $4$ followed by a period, followed by any numeral

Note $-$ Do not enter any space characters inside the regular expression.