human
I found an interesting problem on https://leetcode.com/problems/convert-a-number-to-hexadecimal/:
Given an integer, write an algorithm to convert it to hexadecimal. For negative integer, two’s complement method is used.

Note:

All letters in hexadecimal (a-f) must be in lowercase.
The hexadecimal string must not contain extra leading 0s. If the number is zero, it is represented by a single zero character '0'.
otherwise, the first character in the hexadecimal string will not be the zero character.
The given number is guaranteed to fit within the range of a 32-bit signed integer.
You must not use any method provided by the library which converts/formats the number to hex directly.


Example 1:

Input:
26

Output:
"1a"


Example 2:

Input:
-1

Output:
"ffffffff"

I tried it in Python, but could not do it. Can you solve it?
assistant
#Here is the Python code you requested.

class Solution:
     def toHex(self, num):
         """
         :type num: int
         :rtype: str
         """
         if num == 0:
             return '0'
 
         hexKey = '0123456789abcdef'
         ans = ''
         
         for _ in range(8):
             ans = hexKey[num & 15] + ans
             num >>= 4
 
         return ans.lstrip('0')