old_contents: #!/usr/bin/env python
  
  from nodes import Node
  
  class RickRoll(Node):
      char = "never gonna give you up"
      args = 0
      results = 1
      
      def func(self):
          """Redirect to RickRoll"""
          return "Never gonna let you down"
new_contents: #!/usr/bin/env python
  
  from nodes import Node
  
  class RickRoll(Node):
      char = "Never gonna give you up"
      args = 0
      results = 1
      
      def func(self):
          """Redirect to RickRoll"""
          return "Never gonna let you down"
subject: Rename char