code: def _getClassDefinition(self, ref):
          
          is_ref = ref & REFERENCE_BIT == 0
          ref >>= 1
  
          if is_ref:
              class_def = self.context.getClassByReference(ref)
  
              return class_def
  
          name = self.readBytes()
          alias = None
  
          if name == '':
              name = pyamf.ASObject
  
          try:
              alias = pyamf.get_class_alias(name)
          except pyamf.UnknownClassAlias:
              if self.strict:
                  raise
  
              alias = pyamf.TypedObjectClassAlias(name)
  
          class_def = ClassDefinition(alias)
  
          class_def.encoding = ref & 0x03
          class_def.attr_len = ref >> 2
          class_def.static_properties = []
  
          if class_def.attr_len > 0:
              for i in xrange(class_def.attr_len):
                  key = self.readBytes()
  
                  class_def.static_properties.append(key)
  
          self.context.addClass(class_def, alias.klass)
  
          return class_def
docs: Reads class definition from the stream.