class_docstr: Google Palm Vertexai LLM
  BaseGoogle class is extended for Google Palm model using Vertexai.
  The default model support at the moment is text-bison-001.
  However, user can choose to use code-bison-001 too.
docstr: A method to Validate the Model
code: def _validate(self):
      """
      A method to Validate the Model
  
      """
  
      super()._validate()
  
      if not self.model:
          raise ValueError("model is required.")
  
file_path: pandas-ai/pandasai/llm/google_vertexai.py
imports: from typing import Optional
  from .base import BaseGoogle
  from ..exceptions import UnsupportedModelError
  from ..helpers.optional import import_dependency
label_desc: Use image node_id 4 for calling the GoogleVertexAI obj's underlying member method code with example usage: obj._validate() without return types