code: 
  '''simple docstring'''
  
  UpperCamelCase_     			=       {
      """+""": lambda x, y: x + y,
      """-""": lambda x, y: x - y,
      """*""": lambda x, y: x * y,
      """/""": lambda x, y: x / y,
  }
  
  
  def 	_UpperCAmelCase				(  _lowerCamelCase						:       List[str]		)    ->						str:
    return c.isdigit()
  
  
  def 	_UpperCAmelCase				(  _lowerCamelCase						:       Optional[int]		)    ->						Optional[Any]:
    _lowerCAmelCase       :  Tuple   				=					[]
  
    # iterate over the string in reverse order
    for c in expression.split()[::-1]:
      # push operand to stack
      if is_operand(_lowerCamelCase		):
        stack.append(int(_lowerCamelCase		)		)
  
      else:
        # pop values from stack can calculate the result
        # push the result onto the stack again
        _lowerCAmelCase       :  int   				=					stack.pop()
        _lowerCAmelCase       :  str   				=					stack.pop()
        stack.append(calc[c](_lowerCamelCase  ,      _lowerCamelCase		)		)
  
    return stack.pop()
  
  
  # Driver code
  if __name__ == "__main__":
       UpperCamelCase_     			=       """+ 9 * 2 6"""
       print(evaluate(test_expression))
  
       UpperCamelCase_     			=       """/ * 10 2 + 4 1 """
       print(evaluate(test_expression))
  
  
  
style_context: 
  '''simple docstring'''
  
  from cva import COLOR_BGR2GRAY, cvtColor, imread, imshow, waitKey
  from numpy import divide, inta, multiply, ravel, sort, zeros_like
  
  
  def 	_UpperCAmelCase				(  _lowerCamelCase						:       str  ,      _lowerCamelCase						:       List[Any]=3		)    ->						Union[str, Any]:
    _lowerCAmelCase       :  str   				=					int(mask / 2		)
    # copy image size
    _lowerCAmelCase       :  Dict   				=					zeros_like(_lowerCamelCase		)
    for i in range(_lowerCamelCase  ,      gray_img.shape[0] - bd		):
      for j in range(_lowerCamelCase  ,      gray_img.shape[1] - bd		):
        # get mask according with mask
        _lowerCAmelCase       :  Union[str, Any]   				=					ravel(gray_img[i - bd : i + bd + 1, j - bd : j + bd + 1]		)
        # calculate mask median
        _lowerCAmelCase       :  str   				=					sort(_lowerCamelCase		)[inta(divide((multiply(_lowerCamelCase  ,      _lowerCamelCase		))  ,      2		) + 1		)]
        _lowerCAmelCase       :  Dict   				=					median
    return median_img
  
  
  if __name__ == "__main__":
       # read original image
       UpperCamelCase_     			=       imread("""../image_data/lena.jpg""")
       # turn image in gray scale value
       UpperCamelCase_     			=       cvtColor(img, COLOR_BGR2GRAY)
  
       # get values with two different mask size
       UpperCamelCase_     			=       median_filter(gray, 3)
       UpperCamelCase_     			=       median_filter(gray, 5)
  
       # show result images
       imshow("""median filter with 3x3 mask""", medianaxa)
       imshow("""median filter with 5x5 mask""", medianaxa)
       waitKey(0)
  
  
  