Documentation for sub callwith, assembled from the following types:
callwith calls the next matching candidate with arguments provided by users and returns that candidate's return value.
proto a(|)multi a(Any )multi a(Int )a 1; # OUTPUT: «Int 1␤Any 2␤Back in Int with 5␤»
a 1 calls the most specific
Int candidate first, and
callwith re-dispatches to the less specific
Any candidate. Note that although our parameter
$x + 1 is an Int, still we call the next candidate in the chain.