my %hash1 = ('keyA' => 'valA', 'keyB' => 'valB');
my %hash2 = ('keyA', 'valA', 'keyB', 'valB');
my %hash3 = ('keyA' => 'valA'=> 'keyB' => 'valB');

##</code><code>##

sub mySub {
  my %args = @_
  #... do stuff
}
# and call it equivalently like
mySub ('keyA' => 'valA', 'keyB' => 'valB');
mySub ('keyA', 'valA', 'keyB', 'valB');

##</code><code>##

my $stringA = join ',', %hashA;

#additionally, this is valid (to further demonstrate the point):
my @arrayA = %hashA;