old_contents: """
  plasmapy.errors
  ===============
  
  Custom Errors and Warning names to improve readability
  """
  
  class PhysicsError(Exception):
      """Error for using a deeply troubling physics value"""
      pass
  
  class PhysicsWarning(Warning):
      """Warning for using a mildly worrisome physics value"""
      pass
  
  class RelativityWarning(Warning):
      """Warning for approaching or exceeding the speed of light"""
      pass
new_contents: """
  plasmapy.errors
  ===============
  
  Custom Errors and Warning names to improve readability
  """
  
  class PhysicsError(Exception):
      """Error for using a worrisome physics value"""
      pass
  
  class PhysicsWarning(Warning):
      """Warning for using a mildly worrisome physics value"""
      pass
  
  class RelativityWarning(PhysicsWarning):
      """Warning for approaching or exceeding the speed of light"""
      pass
subject: make RelativityWarning a PhysicsWarning