code: def longest_common(strs, left, right):
      if left == right:
          return strs[left]
      mid = (left + right) // 2
      lcp_left = longest_common(strs, left, mid)
      lcp_right = longest_common(strs, mid + 1, right)
      return common_prefix(lcp_left, lcp_right)
  
label_desc: Use image node_id 5 for calling a global function with example usage: longest_common(strs, left, right) and returns: common_prefix, strs