ls)`): Starting index of each feature map. valid_ratios (`torch.FloatTensor` of shape `(batch_size, num_feature_levels, 2)`): Ratio of valid area in each feature level. output_attentions (`bool`, *optional*): Whether or not to return the attentions tensors of all attention layers. See `attentions` under returned tensors for more detail. output_hidden_states (`bool`, *optional*): Whether or not to return the hidden states of all layers. See `hidden_states` under returned tensors for more detail. return_dict (`bool`, *optional*): Whether or not to return a [`~file_utils.ModelOutput`] instead of a plain tuple. Nru