class_docstr: Edge stores edge details connecting two Vertex instances.
  
  The Edge class supports serialization to a JSON data format expected by the
  client side representation.  When serializing, it generates the following
  fields:
    source_index: The source Vertex index for this Edge.
    target_index: The target Vertex index for this Edge.
    data: Arbitrary data for this Edge.
docstr: Initialize the Edge.
  
  Args:
    idx: The index of the Edge.
docstr_tok: ["Initialize","the","Edge",".","Args",":","idx",":","The","index","of","the","Edge","."]
code: def __init__(self, idx):
      """Initialize the Edge.
  
      Args:
        idx: The index of the Edge.
      """
      self.idx = idx
      self.source = -1
      self.target = -1
      self.data = {}
  
file_path: tensor2tensor/tensor2tensor/insights/graph.py
label_desc: Use image node_id 1 to create a new Edge object from inherited base classes: object with example: obj = Edge(idx)