code: def _validate_pyenv_is_available():
      """
      Validates pyenv is available. If not, throws an `MlflowException` with a brief instruction on
      how to install pyenv.
      """
      url = (
          "https://github.com/pyenv/pyenv#installation"
          if _IS_UNIX
          else "https://github.com/pyenv-win/pyenv-win#installation"
      )
      if not _is_pyenv_available():
          raise MlflowException(
              f"Could not find the pyenv binary. See {url} for installation instructions."
          )
  
imports: import logging
  import os
  import re
  import shutil
  import sys
  import tempfile
  import uuid
  from pathlib import Path
  from packaging.version import Version
  import mlflow
  from mlflow.environment_variables import MLFLOW_ENV_ROOT
  from mlflow.exceptions import MlflowException
  from mlflow.models.model import MLMODEL_FILE_NAME, Model
  from mlflow.utils.conda import _PIP_CACHE_DIR
  from mlflow.utils.databricks_utils import is_in_databricks_runtime
  from mlflow.utils.environment import _CONDA_ENV_FILE_NAME, _PYTHON_ENV_FILE_NAME, _REQUIREMENTS_FILE_NAME, _get_mlflow_env_name, _get_pip_install_mlflow, _PythonEnv
  from mlflow.utils.file_utils import remove_on_error
  from mlflow.utils.process import _IS_UNIX, _exec_cmd, _join_commands
  from mlflow.utils.requirements_utils import _parse_requirements
label_desc: Use image node_id 3 for calling a global function with example usage: _validate_pyenv_is_available() without return types