sub _array_chunk5 {
    my @arr = @_; 
    # Base case == when @arr is <= 5
    return ( join( " ",  @arr ) ) unless @arr > 5;
    # what goes here ?
    return ( join( " ",  splice ( @arr, 0, 5 ) ) , _array_chunk5(@arr) );
}

##</code><code>##

sub _array_chunk5x {
    my @arr = @_; 
    return ( ) if(@arr == 0);
    return ( join( " ", splice( @arr, 0, 5 ) ), _array_chunk5(@arr) );
}