use v6.d;

sub go(Int $x where 1 < $_ < 9) {    # $_ refers to $x
    say $x;
}

go(3);
go(0);

--output:--
3
Constraint type check failed in binding to parameter '$x'; expected anonymous constraint to be met but got Int (0)
  in sub go at b.raku line 4
  in block <unit> at b.raku line 9

##</code><code>##

sub go(Int $x where 1 < * < 9) {
    say $x;
}

go(3);
go(0);

--output:--
3
Constraint type check failed in binding to parameter '$x'; expected anonymous constraint to be met but got Int (0)
  in sub go at b.raku line 4
  in block <unit> at b.raku line 9

##</code><code>##

for <a b c> {say $_};  # shorter version: for <a b c> {.say}
for <a b c> {say *};

--output:--
a
b
c
*
*
*

##</code><code>##

sub MAIN(
  Str   $file where *.IO.f = 'file.dat',
  Int  :$length = 24,
  Bool :$verbose
) {
    say $length if $length.defined;
    say $file   if $file.defined;
    say 'Verbosity ', ($verbose ?? 'on' !! 'off');
}

##</code><code>##

class Foo {
    method bar( $self: ){ "baz" }
};
say Foo.^methods.first(*.name eq 'bar').signature ~~ :($: *%) ;
# OUTPUT: «True&#9252;»