new_contents: import uuid
  
  from simphony.core.data_container import DataContainer
  
  
  class Material(object):
      """A class that represents a material.
  
      Class describes a material and its data.
  
      Attributes
      ----------
      description : str
          textual description of the material
      uid : uuid.UUID
          the id of the material.
      data : DataContainer
          data associated with this material
  
      """
      def __init__(self, uid=None, data=None, description=""):
          self.data = data if data else DataContainer()
          self.uid = uid if uid else uuid.uuid4()
          self.description = description
  
subject: Add Material class