Test if an object can be coerced to a given S4 class.
Maybe useful inside
if() to ensure that calling
as(object, Class) will find a method.
any R object, typically of a formal S4 class.
an S4 class (see
a scalar logical,
TRUE if there is a
(as defined by e.g.
setAs) for the signature
(from = class(object), to = Class).
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