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// If you know from external means that an expression is not null or undefined,
// you can use the non-null assertion operator ! to coerce away those types
// operator docs: https://www.typescriptlang.org/docs/handbook/2/everyday-types.html#non-null-assertion-operator-postfix-
// Error, some.expr may be null or undefined
let x = some.expr.thing;
// OK
let y = some.expr!.thing;