human
Can you provide a the Python code you requested given the following:
Solve in Python:
A sequence of numbers is called a wiggle sequence if the differences between successive numbers strictly alternate between positive and negative. The first difference (if one exists) may be either positive or negative. A sequence with fewer than two elements is trivially a wiggle sequence. 

For example, [1,7,4,9,2,5] is a wiggle sequence because the differences (6,-3,5,-7,3) are alternately positive and negative. In contrast, [1,4,7,2,5] and [1,7,4,5,5] are not wiggle sequences, the first because its first two differences are positive and the second because its last difference is zero.

Given a sequence of integers, return the length of the longest subsequence that is a wiggle sequence. A subsequence is obtained by deleting some number of elements (eventually, also zero) from the original sequence, leaving the remaining elements in their original order.

Examples:

Input: [1,7,4,9,2,5]
Output: 6
The entire sequence is a wiggle sequence.

Input: [1,17,5,10,13,15,10,5,16,8]
Output: 7
There are several subsequences that achieve this length. One is [1,17,10,13,10,16,8].

Input: [1,2,3,4,5,6,7,8,9]
Output: 2


Follow up:
Can you do it in O(n) time?

Credits:Special thanks to @agave and @StefanPochmann for adding this problem and creating all test cases.
assistant
#Here is the Python code you requested.

class Solution:
     def wiggleMaxLength(self, nums):
         """
         :type nums: List[int]
         :rtype: int
         """
         l = len(nums)
         if l == 0:
             return 0
         elif l == 1:
             return 1
         st = 1
         while nums[0] == nums[st]:
             st += 1
             if st == l:
                 return 1
         seq = [nums[0], nums[st]]
         for i in range(st+1, l):
             if nums[i] == seq[-1]:
                 continue
             if seq[-1] < seq[-2]:
                 if nums[i] < seq[-1]:
                     seq[-1] = nums[i]
                 else:
                     seq.append(nums[i])
             else:
                 if nums[i]>seq[-1]:
                     seq[-1] = nums[i]
                 else:
                     seq.append(nums[i])
         return len(seq)