my $returned = some_func($sent);
  # ...
  sub some_func
  {
    my $received = shift;
    # ...
    $value;
  }

##</code><code>##

  my $returned = Foo::Bar::some_func($sent);
  # in Foo::Bar:
  sub some_func
  {
    my $received = shift;
    #...
    $value;
  }

##</code><code>##

  my $returned = Foo::Bar->some_func($sent);
  # in Foo::Bar (or any package that Foo::Bar derives from)
  sub some_func
  {
    my $class_name = shift; # will be Foo::Bar, even if we aren't in that package right now
    my $received = shift;
    # ...
    $value
  }

##</code><code>##

  my $returend = $obj->some_func($sent);
  # in the package that $obj is blessed into, or any package it is derived from
  sub some_func
  {
    my $self = shift;
    my $received = shift;
    #...
    $value;
  }