old_contents: from .models import Node, Info, Transmission
  from sqlalchemy import ForeignKey, Column, String
  import random
  
  
  class Source(Node):
      __tablename__ = "source"
      __mapper_args__ = {"polymorphic_identity": "generic_source"}
  
      uuid = Column(String(32), ForeignKey("node.uuid"), primary_key=True)
  
      def _selector(self):
          return []
  
      def create_information(self):
          """Generate new information."""
          return NotImplementedError
  
      def transmit(self, other_node, selector=None):
  
          if selector is None:
              cls = Info
  
          elif issubclass(selector, Info):
              cls = selector
  
          info = cls(
              origin=self,
              origin_uuid=self.uuid,
              contents=self._data())
  
          super(Source, self).transmit(other_node, selector=info)
  
      def broadcast(self):
          for vector in self.outgoing_vectors:
              self.transmit(vector.destination, selector=Info)
  
  
  class RandomBinaryStringSource(Source):
      """An agent whose genome and memome are random binary strings. The source
      only transmits; it does not update.
      """
  
      __mapper_args__ = {"polymorphic_identity": "random_binary_string_source"}
  
      @staticmethod
      def _data():
          return "".join([str(random.randint(0, 1)) for i in range(2)])
  
new_contents: from .models import Node, Info, Transmission
  from sqlalchemy import ForeignKey, Column, String
  import random
  
  
  class Source(Node):
      __tablename__ = "source"
      __mapper_args__ = {"polymorphic_identity": "generic_source"}
  
      uuid = Column(String(32), ForeignKey("node.uuid"), primary_key=True)
  
      def _selector(self):
          return []
  
      def create_information(self):
          """Generate new information."""
          return NotImplementedError
  
  
  class RandomBinaryStringSource(Source):
      """An agent whose genome and memome are random binary strings. The source
      only transmits; it does not update.
      """
  
      __mapper_args__ = {"polymorphic_identity": "random_binary_string_source"}
  
      @staticmethod
      def _data():
          return "".join([str(random.randint(0, 1)) for i in range(2)])
  
subject: Remove redundant stuff!