memorised | memcache memoization decorators and utils for python

I need to print characters which come before the fifth
in a PHP string.

e.g. The string is:

I am doing tensorflow object detection and I find that there are lot of false positives. One of the main reasons that I see for this is the case of overfitting. But my doubt is how does false positive become a result of overfitting? The overfitting happens when it learns a complex pattern in data or in short it leads to memorisation of the data.

If it was memorisation, wouldn't it show more false negatives as it has only memorised the training data and is unable to detect new cases. How can it really classify other objects as belonging to trained class is it not counter intuitive?

I want some code for a task that requires users to memorise a number. The task should work as follows:

The user is directed to press down a combination of three keys in order to display the number they need to remember. These can be any three keys as long as it will require the user to use both hands (the idea being that this will prevent them from writing down the number they are supposed to be memorising).

When they begin to hold down the keys, the number is displayed and a timer starts. If they keep holding down the keys for the requisite period of time (15 seconds), a function runs automatically (this is another task they have to do while remembering the number).

However, if they release the keys before the 15 seconds is up, a different function runs. This function just informs them that they released the keys too early, and when they click on a button the task restarts with a new number.

The code I currently have looks like this: