A string, one of channels_last (default) or channels_first.
The ordering of the dimensions in the inputs.
channels_last corresponds to inputs with shape
(batch, ..., channels) while channels_first corresponds to
inputs with shape (batch, channels, ...).
Examples:
x=tf.compat.v1.placeholder(shape=(None,4,4),dtype='float32')y=Flatten()(x)# now `y` has shape `(None, 16)`x=tf.compat.v1.placeholder(shape=(None,3,None),dtype='float32')y=Flatten()(x)# now `y` has shape `(None, None)`