input: from typing import List
  
  class MedianFinder:
      def __init__(self):
          """
          Initialize the MedianFinder class with an empty list to store numbers.
          """
          self._data = []
  
      def add(self, num: float):
          """
          Add a number to the internal list.
          """
          self._data.append(num)
  
      def find_median(self) -> float:
          """
          Find the median of the current list of numbers.
          >>> median_finder = MedianFinder()
          >>> median_finder.add(1)
          >>> median_finder.add(2)
          >>> median_finder.find_median()
          1.5
          >>> median_finder.add(3)
          >>> median_finder.find_median()
          2.0
          """
          data = sorted(self._data)
          n = len(data)
          return (data[(n - 1) // 2] + data[n // 2]) / 2
output:     
          data = sorted(self._data)
          n = len(data)
          if n % 2 == 0:
              return (data[n // 2 - 1] + data[n // 2]) / 2
          else:
              return data[n // 2]
  