smallest unit of concurrency that I can think of, with more detail:

wrapper {
    var mutable flag
    CALL λ₁
    CLR flag
loop:
    TEST flag
    BRNZ exit
    CALL λ₂
    BR loop
exit:
    CALL λ₃
}
λ₁ - begin
λ₂ - message handler
λ₃ - finish
λ₁ (self, &rest args)
λ₂ (self, message)
λ₃ (self)

See Also

Smallest Unit of Concurrency

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