Calculate summer/winter time of EU+US

I need the calculation of the summer/winter time dates in the EU and in the US based on the current year.
The calculation must also work in the strategy tester.
The 4 calculated dates must be stored in variables of type datetime.

For this I would like to have 4 individual functions, where each individual function calculates one of the dates.
- Function 1: Date of the start of daylight saving time in EU = starts last Sunday in March.
- Function 2: Date of the start of daylight saving time in the US = Starts on the 2nd Sunday in March.
- Function 3: Date of the start of winter time in the EU = Starts on the last Sunday in October.
- Function 4: Date of the start of winter time in the US = Starts on the 1st Sunday in November.

The EA should be able to calculate all 4 days mentioned above on any day of the year and store them in a variable as datetime.

To make my wish clearer, I have roughly prepared an EA.
In it I show the structure as I would like it to be.
In the 4 functions, the return 0 must of course be replaced with the calculated values.
The structure only serves as an overview so that I can better explain my wish.
Modifying the EA with clean and working code is up to you.

Please take a look to the atached ea / file.