code: def proximity_metric(self, a, b):
          
          # if self._is_pylib(a) and self._is_pylib(b):
          #     return 1
  
          res = 1
          for ap, bp, n in zip(a.path_parts, b.path_parts, list(range(4))):
              res += ap == bp
              if n >= 3:
                  break
          return res
docs: Return the weight of the dependency from a to b. Higher weights
             usually have shorter straighter edges. Return 1 if it has normal
             weight. A value of 4 is usually good for ensuring that a related
             pair of modules are drawn next to each other.
  
             Returns an int between 1 (unknown, default), and 4 (very related).