##
my @big_in_assoc_1 = grep keys %{$assocs_1{$_}} > 25, keys %assocs_2;
# ... tics later
my @relative_complement = grep !exists %assocs_1{$_}, keys %assocs_2; # OUCH!
##
##
my $number_of_entities = grep defined $hoh{$_}, keys %hoh;
##
##
my @big_in_assoc_1 =
grep $assocs_1{$_} && keys %{$assocs_1{$_}} > 25,
keys %assocs_2;