Flatten classkeras.layers.Flatten(data_format=None, **kwargs)
Flattens the input. Does not affect the batch size.
Note: If inputs are shaped (batch,) without a feature axis, then
flattening adds an extra channel dimension and output shape is (batch, 1).
Arguments
"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, ...).
  When unspecified, uses image_data_format value found in your Keras
  config file at ~/.keras/keras.json (if exists). Defaults to
  "channels_last".Example
>>> x = keras.Input(shape=(10, 64))
>>> y = keras.layers.Flatten()(x)
>>> y.shape
(None, 640)