I have to write a program which generates a pascal's triangle.

The user inputs the height of the triangle and it supposed to generate one.

This is what I have so far and I don't know how you would keep

adding rows after the second one. I'm so lost :(

```
numStr = raw_input("Please input the height of Pascal's Triangle: ")
row = int(numStr)
tri = []
row1 = [1]
row2 = [1, 1]
tri.append(row1)
tri.append(row2)
while len(tri) < row:
print tri
break
```