my $document = MyApp::Note->new(
        to_collection => [MyApp::To->new(text => 'Bob')],
        from_collection => [MyApp::From->new(text => 'Alice')],
        headings => [MyApp::Heading->new(text => 'Secret' )],
        body_collection => [MyApp::Body->new(text=>'Shh!')],
    )

##</code><code>##

coerce 'MyApp::To' 
    => from 'Str' 
    => via { MyApp::To->new(text => $_) };
coerce 'MyApp::From' 
    => from 'Str' 
    => via { MyApp::From->new(text => $_) };
coerce 'MyApp::Heading' 
    => from 'Str' 
    => via { MyApp::Heading->new(text => $_) };
coerce 'MyApp::Body' 
    => from 'Str' 
    => via { MyApp::Body->new(text => $_) };