python 'module' - for png tiles out of my folder

Question

This is my code

import pygame

pygame.init()

class Tiles:

    size = 32

    def Load_Texture(file, size):
        bitmap = pygame.image.load(file)
        bitmap = pygame.transform.scale(bitmap, (size, size))
        surface = pygame.surface((size, size), pygame.HWSURFACE|pygame.SRCALPHA)
        surface.blit(bitmap, (0, 0))
        return surface

    grass = Load_Texture("graphs\\grass.png", size)

    stone = Load_Texture("graphs\\stone.png", size)

    water = Load_Texture("graphs\\water.png", size)

and this is the error report

PS C:\Users\shuyi\Desktop\Programming\Python\RPG> & python c:/Users/shuyi/Desktop/Programming/Python/RPG/scripts/textures.py
Traceback (most recent call last):
  File "c:/Users/shuyi/Desktop/Programming/Python/RPG/scripts/textures.py", line 5, in <module>
    class Tiles:
  File "c:/Users/shuyi/Desktop/Programming/Python/RPG/scripts/textures.py", line 16, in Tiles
    grass = Load_Texture("graphs\\grass.png", size)
  File "c:/Users/shuyi/Desktop/Programming/Python/RPG/scripts/textures.py", line 12, in Load_Texture
    surface = pygame.surface((size, size), pygame.HWSURFACE|pygame.SRCALPHA)
TypeError: 'module' object is not callable
PS C:\Users\shuyi\Desktop\Programming\Python\RPG>

I dont understand why I get this error :(

could anyone pls explain this for me? I cant find a fitting solution on the net