Edge->new(); # all properties set to undef
Edge->new("from_node","to_node"); # label set to undef
Edge->new("from_node","to_node","label"); # all props set

##</code><code>##

sub new()
{
  my $class = shift;
  my $self = {};
  $self->{'from_node'} = undef;
  $self->{'to_node'} = undef;
  $self->{'label'} = undef;
  bless $self, $class;
  return $self;
}