code: def to_array(self):
      return np.array([self.start, self.end])
  
imports: import numpy
  from dataclasses import dataclass
  from typing import List, NamedTuple
  from jiant.tasks.core import FeaturizationSpec
  from jiant.tasks.utils import truncate_sequences, pad_to_max_seq_length
  from jiant.utils.python.datastructures import BiMap
label_desc: Use image node_id 3 for calling the Span obj's underlying member method code with example usage: obj.to_array() and returns: np