Time

The following is true for nested$-$if :

a$.$ it needs at least an outer if expression and at least an inner if expression

b$.$ it can be an outer if without an inner if $($just have an inner else$)$

c$.$ the outer if can be false so the nested if occurs inside the outer else

d$.$ it is an if$-$else cormbination with another if$-$else inside the the outer if

e$.$ whatever happened, the outer if expression must be true in order to create a nested if