src/transformers/models/lxmert/modeling_lxmert.py/LxmertVisualFeatureEncoder/__init__
class LxmertVisualFeatureEncoder:    def __init__(self, config):
        super().__init__()
        feat_dim = config.visual_feat_dim
        pos_dim = config.visual_pos_dim

        # Object feature encoding
        self.visn_fc = nn.Linear(feat_dim, config.hidden_size)
        self.visn_layer_norm = nn.LayerNorm(config.hidden_size, eps=1e-12)

        # Box position encoding
        self.box_fc = nn.Linear(pos_dim, config.hidden_size)
        self.box_layer_norm = nn.LayerNorm(config.hidden_size, eps=1e-12)

        self.dropout = nn.Dropout(config.hidden_dropout_prob)