# while naming a sub like in:
defined &my_sub_name;

# doing indirect sub call (but $subref->() is another valid option)
&$subref();

# making a reference to a sub
$coderef   = \&handler;


##</code><code>##

    &foo(1,2,3);    # pass three arguments
    foo(1,2,3);     # the same
    foo();          # pass a null list
    &foo();         # the same
    &foo;           # foo() get current args, like foo(@_) !!
    foo;            # like foo() IFF sub foo predeclared, else "foo"