Pyramid Array

DESCRIPTION:

Write a function that when given a number >= 0, returns an Array of ascending length subarrays.

pyramid(0) => [ ]
pyramid(1) => [ [1] ]
pyramid(2) => [ [1], [1, 1] ]
pyramid(3) => [ [1], [1, 1], [1, 1, 1] ]

Note: the subarrays should be filled with 1s

---

def pyramid(n):
    ans=[]
    alist=[]
    for i in range(1,n+1):
        alist.append(1)
        ans.append(alist.copy())
    return ans