D-Flat | domain graphics

I am learning how to use proxy models recently， And I want to create a custom proxy model that can flat nodes in a source tree model to a list model, I have found a good solution to this: How to create a proxy model that would flatten nodes of a QAbstractItemModel into a list in PySide?

However, when I try to removeRows() (remove tree node) from the source tree model, the proxy model crashes, I guess it's because the source model didn't emit layoutChanged signal to the proxy model to refresh the self.m_rowMap and self.m_indexMap?

【question1】: How to fix the crash?

【question2】:For QSortFilterProxyModel, removeRows() from the source model won't crash the proxy model, so I also want to know the underlying mechanism of QSortFilterProxyModel, especially the implementation of the following methods:

First off, I know next to nothing about Mac development. I'm a Windows developer. Upon finding out that there is no easy way to do what I'm about to tell you in C#, I thought maybe it is time to learn Swift. However, I want to make sure that this is easily possible before I go out and buy a Mac and learn Mac development.

I have a piano keyboard that has a USB port on the back. When I plug my piano into my iPhone using the USB-to-Lightning adapter and open GarageBand for iOS, when I play a key on my piano, that key plays on my iPhone! I want to do something similar using the same technology (which, upon research, I believe to be MIDI) to make an app where when I press a key on my piano, the Mac will do a certain command depending on what key was pressed. For example, if the D key was pressed, a popup box would come and say "You pressed D-flat!".

As far as I know, there is no easy way to do this in C# without installing some shady third-party library off the internet that nobody has ever heard of before. I figured that since Apple makes GarageBand and is more used in the music industry than PC, there might be an easier way to do something like this.

I'm looking to do something like this:

Trying to scrape floor sizes (in sq ft) and lot sizes (in hectares) from listings on a real estate website using Beautiful Soup and Selenium.

The floor sizes print fine in the console

but when writing to a csv file the the 'sq ft' info under the floor size column is not extracted

It seems if 'sq ft' is found by BS4 in the ID element after the the one stipulated, that is returned instead and all other 'sq ft' text is passed over on every other url when writing to the csv. As you can see on (image) two of the listings have this, despite those two links having hectares as well:

http://property.shw.co.uk/propertyInfo/11080/145151-London-Road-Croydon--CR0-2RG http://property.shw.co.uk/propertyInfo/16162/Public-HouseRestaurant-Site-Westvale-Park-Horley-Surrey--RH6-0HJ

Can someone explain why the sq ft are printed on the console but not written to the csv? Any help would be appreciated.

Relevant HTML where CP2_CPContent_conDetails1_divDetails is relevant locator for floor sizes and lot sizes: