exit status: 1 with stderr:
<stdin>:3:15: error: immutable value 'x' may only be initialized once async let x = 42 // Immutable value 'x' may only be initialized once ^ <stdin>:3:19: note: initial value already provided in 'let' declaration async let x = 42 // Immutable value 'x' may only be initialized once ^ <stdin>:3:15: note: change 'let' to 'var' to make it mutable async let x = 42 // Immutable value 'x' may only be initialized once ^~~ var