as.list method for by Objects

Good day,

I'd like to suggest the addition of an as.list method for a by object that
actually returns a list of class "list". This would make it safer to do
type-checking, because is.list also returns TRUE for a data.frame variable
and using class(result) == "list" is an alternative that only returns TRUE
for lists. It's also confusing initially that

class(x)

[1] "by"

is.list(x)

[1] TRUE

since there's no explicit class definition for "by" and no mention if it
has any superclasses.

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Dario Strbenac
University of Sydney
Camperdown NSW 2050
Australia