A parameter of a function, as its signature declares it: a primitive type, [1], or [0..1] when it may be left empty (PLAN §6.5)
[1]
[0..1]
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[0..1]: an empty value is passed as []
[]
A parameter of a function, as its signature declares it: a primitive type,
[1], or[0..1]when it may be left empty (PLAN §6.5)