class_docstr: A tuple of `InfDim`s.
  
  This is intended to be attached to each parameter tensor `p` as `p.infshape`.
code: def fanin_fanout_mult_ratio(self):
      fanin, fanout = self.fanin_fanout()
      return fanin.width_mult() / fanout.width_mult()
  
imports: from copy import copy
label_desc: Use image node_id 3 for calling the InfShape obj's underlying member method code with example usage: obj.fanin_fanout_mult_ratio() and returns: unknown