Visual Stack trace of recursive fibonacci function

fib_rec.py

class HorizontalPrint:
    def __init__(self):
        self.y = 0
        self.buffer = [""]

    def print(self, v: str):
        self.buffer[self.y] += v
        self.y += 1

        if len(self.buffer) <= self.y:
            self.buffer.append("")

    def end_block(self):
        self.y = 0

        # allignment
        max_x = max(map(len, self.buffer)) + 1#padding
        self.buffer = list(map(lambda v: v + " "*(max_x - len(v)), self.buffer))

    def flush(self):
        for c in self.buffer:
            print(c)

class Stack:
    def __init__(self, logger: HorizontalPrint):
        self.stack = []
        self.logger = logger

    def print(self):
        self.logger.print("=======")
        for value in self.stack:
            self.logger.print(f"|{value}")

        self.logger.print("=======")
        self.logger.end_block()

    def push(self, value: str):
        self.stack.append(value)
        self.print()

    def pop(self):
        self.stack.pop()
        self.print()

def fib(n: int, stack: Stack):
    stack.push(f"fib({n})")

    if n == 0: result = 0
    elif n == 1: result = 1
    else: result = fib(n - 1, stack) + fib(n - 2, stack)

    stack.pop()

    return result

hp = HorizontalPrint()
fib(5, Stack(hp))
hp.flush()