exit status: 1 with stderr:
<stdin>:3:13: error: definition conflicts with previous value guard let a = a else { return } ^ <stdin>:2:7: note: previous definition of 'a' is here var a: Int? = 1 ^ <stdin>:4:7: error: value of optional type 'Int?' must be unwrapped to a value of type 'Int' _ = a + 1 ^ <stdin>:4:7: note: coalesce using '??' to provide a default when the optional value contains 'nil' _ = a + 1 ^ ?? <#default value#> <stdin>:4:7: note: force-unwrap using '!' to abort execution if the optional value contains 'nil' _ = a + 1 ^ !