def newLayer(self, effect=''):
		"""
		Creates a new :py:class:`Layer` and set that as the active.
		
		:param effect: A string with the blend mode for that layer that will be used when during the rendering process. The accepted values are: :code:`'soft_light','lighten','screen','dodge','addition','darken','multiply','hard_light','difference','subtract','grain_extract','grain_merge','divide','overlay'`.
		:rtype: Nothing.
		"""
		self.layers.append(Layer(effect = effect))
		self.activeLayer = len(self.layers)-1