Roman to Integer

My Solution

Python

def romanToInt(s: str) -> int:
        basis = {
                "I": 1,
                "V": 5,
                "X": 10,
                "L": 50,
                "C": 100,
                "D": 500,
                "M": 1000,
        }

        nums = list(s)
        value = i = 0

        while i < len(nums):
                if i == len(nums) - 1 or basis[nums[i]] >= basis[nums[i+1]]:
                        value += basis[nums[i]]
                        i+=1
                else:
                        value += (basis[nums[i+1]] - basis[nums[i]])
                        i+=2

        return value