code: def _overlap(x1, w1, x2, w2):
      l1 = x1 - w1 / 2
      l2 = x2 - w2 / 2
      left = l1 if l1 > l2 else l2
      r1 = x1 + w1 / 2
      r2 = x2 + w2 / 2
      right = r1 if r1 < r2 else r2
      return right - left
  
imports: from __future__ import division
  import math
  from collections import namedtuple
  from functools import cmp_to_key
  import numpy
label_desc: Use image node_id 3 for calling a global function with example usage: _overlap(x1, w1, x2, w2) and returns: unknown