SetKeepInMemory is not exposed on SBExpressionOptions which prevents saving persistent variables across expressions in the Python API

[BlueFalconHD]

In the source for the expr command, LLDB sets the SetKeepInMemory flag on ExpressionOptions which allows something like:

(lldb) expr -l ObjC --
int (^$double)(int) = ^int(int num) {
return num*2;
};

(lldb) expr -l ObjC -- $double(2);
(int) $1 = 4

However, doing the same via the Python API is not possible, there is no switch on SBExpressionOptions to keep a variable saved for future expressions.