my $val = "foo";
my $valref = \$val;
my @valarray = ("foo");
my %valhash = ( somekey => 'foo' );
my %otherhash = ( foo => 'dummy_value' );
allvars($val);
allvars($$valref);
allvars($valarray[0]);
allvars(@valarray);
allvars("foo");
allvars(join '', map { chr } (102,111,111));
allvars($valhash{somekey});
allvars(keys %otherhash);

##</code><code>##

my $params = {
  this => 'foo',
  that => 'bar',
  other => 'baz',
}
sub param_names {
  my $params = shift;
  print "$_: $params->{$_}\n" for keys %$params;
}

param_names($params);