class_docstr: Linear layer implementation with per-group 4-bit quantization of the weights
code: def forward(self, x):
      out = ext_q4_matmul(x, self.q4, self.width)
  
      if self.bias is not None:
          out.add_(self.bias)
      return out
  
file_path: text-generation-inference/server/text_generation_server/utils/gptq/exllama.py
imports: import torch
  from exllama_kernels import make_q4, q4_matmul, prepare_buffers, set_tuning_params
label_desc: Use image node_id 2 for calling the Ex4bitLinear obj's underlying member method code with example usage: obj.forward(x) and returns: out