class_docstr: Generates the cycle motif from the `"GNNExplainer:
  Generating Explanations for Graph Neural Networks"
  <https://arxiv.org/abs/1903.03894>`__ paper.
  
  Args:
      num_nodes (int): The number of nodes in the cycle.
code: def __repr__(self) -> str:
      return f"{self.__class__.__name__}({self.num_nodes})"
  
imports: import torch
  from torch_geometric.data import Data
  from torch_geometric.datasets.motif_generator import CustomMotif
label_desc: Use image node_id 2 for calling the CycleMotif obj's underlying member method code with example usage: obj.__repr__() and returns: self, str, self, str