Leetcode: Remove Element @Python

class Solution:
    # @param    A       a list of integers
    # @param    elem    an integer, value need to be removed
    # @return an integer
    def removeElement(self, A, elem):
        n=len(A)
        for i in reversed(range(n)):
            if A[i]==elem:
                A.pop(i)
                n-=1
        return n