ASP.net Web page error Use of unassigned local variable 'some'

ASP.net Web page error Use of unassigned local variable 'some'

I have razor code like this
bool some;
if (IsPost == false)
{
some = True
}
then html
<h1>@some.ToString()</h1>
and when i run it it get's me error Use of unassigned local variable 'some'
could anyone explain why? doesn't razor code executes first and then html?