Adding Site Collection Administrators programatically

One of my team mates had a question whether we can add site collection Administrators to the site through object model.
Its fairly simple and easy.
code chunks:
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SPSite _site = null;
SPUser user = null;
SPWeb _web = null;
try
{

SPSecurity.RunWithElevatedPrivileges(delegate()
{

_site = new SPSite("siteURL");

_web = _site.OpenWeb();
_web.AllowUnsafeUpdates = true;
_web.SiteUsers.Add(@"mossbox\user1", "user1@email.com", "user1", "Added via object model");
_web.Update();
user = _web.SiteUsers[@"mossbox\user1"];
_site.SecondaryContact = user;
user.Update();
_web.AllowUnsafeUpdates = false;
});
}
catch (Exception ex)
{

MessageBox.Show("Error in Adding Site Collection Administrators " + ex.Message.ToString());


}
finally
{
if (_site != null)
{
_site.Dispose();
}
if (_web != null)
{
_web.Dispose();
}

}


}

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