Flush each print() call

Hi Alex,
Imagine the following code:
'''
print(1)
print(2)
print(3)
'''

Currently the output from these prints will accumulate in the OutputBuffer and sent according to its function should_flush.
I'm trying to flush immediately after each print().
I would overwrite the should_flush function, but since the Runner class has an instance of the OutputBuffer, I don't know how to overwrite that from the outside without rewriting the OutputBuffer class.

Is there a recommended way of changing the conditions for flushing?

The Big Picture is to build a custom debugger, thus needing to stop execution after each line of code.

Kind regards,
Jeff