code: def build(self):
      encoders = self._build_encoders(self.config)
      # Text Encoder mode
      if "modal_encoder" not in self.config:
          self.encoder = encoders[0]
      # Modal encoder mode
      elif "text_encoder" not in self.config:
          self.encoder = encoders[1]
      else:
          raise RuntimeError(
              "Unimodal Encoder can't have both text and modal encoder"
          )
  
imports: import collections
  from copy import deepcopy
  import torch
  from mmf.common.registry import registry
  from mmf.models.base_model import BaseModel
  from mmf.modules.encoders import MultiModalEncoderBase
  from mmf.utils.build import build_classifier_layer
label_desc: Use image node_id 2 for calling the UnimodalBase obj's underlying member method code with example usage: obj.build() without return types