Thanks in advance.

I am wriiting a code about Conway's game of life,and i am a beginner of python,have looked at my code for hours,still couldnt find out the bug...when i run it,it doesnt work....only return the same matrix as the test code given..anybody can help with check it would be very helpful.

here is my code:

```
'''If a cell is dead at time T with exactly three live neighbours, the cell will be alive at T+1
If a cell is alive at time T with less than two living neighbours it dies at T+1
If a cell is alive at time T with more than three live neighbours it dies at T+1
If a cell is alive at time T with exactly two or three live neighbours it remains alive at T+1'''
import numpy
def apply_rules (universe_array):
height, width = universe_array.shape
# create a new array for t+1
evolved_array = numpy.zeros((height, width),numpy.uint8)
for iy in range(1, height-1):
for ix in range(1,width-1):
neighbours=0
if universe_array[iy-1,ix-1]==1:
neighbours+=1
if universe_array[iy,ix-1]==1:
neighbours+=1
if universe_array[iy+1,ix-1]==1:
neighbours+=1
if universe_array[iy-1,ix]==1:
neighbours+=1
if universe_array[iy+1,ix]==1:
neighbours+=1
if universe_array[iy-1,ix+1]==1:
neighbours+=1
if universe_array[iy,ix+1]==1:
neighbours+=1
if universe_array[iy+1,ix+1]==1:
neighbours+=1
if universe_array[iy,ix]==0 and neighbours==3:
evolved_array[iy,ix]==1
if universe_array[iy,ix]==1 and neighbours<2:
evolved_array[iy,ix]==0
if universe_array[iy,ix]==1 and neighbours>3:
evolved_array[iy,ix]==0
if universe_array[iy,ix]==1 and (neighbours==2 or neighbours==3):
evolved_array[iy,ix]=universe_array[iy,ix]
return evolved_array
if __name__ == "__main__":
a = numpy.zeros((4,4),numpy.uint8)
a[1,1]=1
a[1,2]=1
a[2,1]=1
print a
b= apply_rules(a)
print b
```