DB<191> *PCKG::unknown{ARRAY}
 => undef
 
  DB<192> @PCKG::foo=(1,2,3)
 => (1, 2, 3)
 
  DB<193> *PCKG::foo{ARRAY}
 => [1, 2, 3]
 
  DB<194> *PCKG::foo{SCALAR}        # why \undef and not undef ???
 => \undef
 
  DB<195> $PCKG::foo=undef
 => undef
 
  DB<196> *PCKG::foo{SCALAR}        # same effect
 => \undef
 
  DB<198> undef $PCKG::foo
 => undef
 
  DB<199> *PCKG::foo{SCALAR}        # again
 => \undef