code: def find_prefix_at_end(haystack, needle):
      l = len(needle) - 1
      while l and not haystack.endswith(needle[:l]):
          l -= 1
      return l
  
imports: import asyncore
  from collections import deque
  from warnings import _deprecated
label_desc: Use image node_id 1 for calling a global function with example usage: find_prefix_at_end(haystack, needle) and returns: l