code: def get_single_data(self):
      # Ensure that the stream contains a single document and construct it.
      node = self.get_single_node()
      if node is not None:
          return self.construct_document(node)
      return None
  
imports: from .error import *
  from .nodes import *
  import collections.abc, datetime, base64, binascii, re, sys, types
label_desc: Use image node_id 5 for calling the BaseConstructor obj's underlying member method code with example usage: obj.get_single_data() and returns: None, self