(What happens in blessed arrayrefs which overload hashrefification? Or blessed hashrefs which overload arrayfication? Or blessed scalar refs which overload both?!)

push $blessed_hashref_or_arrayref, ...
results in:
"Not an ARRAY reference" or
"Not an unblessed ARRAY reference"

each $blessed_hashref_or_arrayref
results in:
"Type of argument to each on reference must be unblessed hashref or arrayref"