class_docstr: Generates random Barabasi-Albert (BA) graphs.
  See :meth:`~torch_geometric.utils.barabasi_albert_graph` for more
  information.
  
  Args:
      num_nodes (int): The number of nodes.
      num_edges (int): The number of edges from a new node to existing nodes.
code: def __call__(self) -> Data:
      edge_index = barabasi_albert_graph(self.num_nodes, self.num_edges)
      return Data(num_nodes=self.num_nodes, edge_index=edge_index)
  
imports: from torch_geometric.data import Data
  from torch_geometric.datasets.graph_generator import GraphGenerator
  from torch_geometric.utils import barabasi_albert_graph
label_desc: Use image node_id 2 for calling the BAGraph obj's underlying member method code with example usage: obj.__call__() and returns: Data