src/transformers/models/vit_hybrid/modeling_vit_hybrid.py/ViTHybridPooler/__init__
class ViTHybridPooler:    def __init__(self, config: ViTHybridConfig):
        super().__init__()
        self.dense = nn.Linear(config.hidden_size, config.hidden_size)
        self.activation = nn.Tanh()