void BeginMethodBody(IType returnType)
{
_defaultValueHolders.Clear();
_returnType = returnType;
_returnStatements = 0;
_returnImplicit = IsVoid(returnType);
_hasLeaveWithStoredValue = false;
//we may not actually use (any/all of) them, but at least they're ready
_returnLabel = _il.DefineLabel();
_leaveLabel = _il.DefineLabel();
_implicitLabel = _il.DefineLabel();
}