See https://pub.dev/packages/quiver instead!
Argument, state and other invariant checks for your programs.
checkArgument
throws ArgumentError
if the specified argument check expression
is false.
checkListIndex
throws RangeError
if the specified index is out of bounds.
checkNotNull
throws ArgumentError
if the specified argument is null.
checkState
throws StateError
if the specified state check expression is
false.