code: def auto_response_ssst(
      gtab, data, roi_center=None, roi_radii=10, fa_thr=0.7
  ):
      """Automatic estimation of single-shell single-tissue (ssst) response
          function using FA.
  
      Parameters
      ----------
      gtab : GradientTable
      data : ndarray
          diffusion data
      roi_center : array-like, (3,)
          Center of ROI in data. If center is None, it is assumed that it is
          the center of the volume with shape `data.shape[:3]`.
      roi_radii : int or array-like, (3,)
          radii of cuboid ROI
      fa_thr : float
          FA threshold
  
      Returns
      -------
      response : tuple, (2,)
          (`evals`, `S0`)
      ratio : float
          The ratio between smallest versus largest eigenvalue of the response.
  
      Notes
      -----
      In CSD there is an important pre-processing step: the estimation of the
      fiber response function. In order to do this, we look for voxels with very
      anisotropic configurations. We get this information from
      csdeconv.mask_for_response_ssst(), which returns a mask of selected voxels
      (more details are available in the description of the function).
  
      With the mask, we compute the response function by using
      csdeconv.response_from_mask_ssst(), which returns the `response` and the
      `ratio` (more details are available in the description of the function).
      """
  
      mask = mask_for_response_ssst(
          gtab, data, roi_center, roi_radii, fa_thr
      )
      response, ratio = response_from_mask_ssst(gtab, data, mask)
  
      return response, ratio
  
imports: import warnings
  import numpy
  import numbers
  from scipy.integrate import quad
  from scipy.special import lpn, gamma
  import scipy.linalg
  import scipy.linalg.lapack
  from dipy.data import small_sphere, get_sphere, default_sphere
  from dipy.core.geometry import cart2sphere
  from dipy.core.ndindex import ndindex
  from dipy.sims.voxel import single_tensor
  from dipy.reconst.multi_voxel import multi_voxel_fit
  from dipy.reconst.dti import TensorModel, fractional_anisotropy
  from dipy.reconst.shm import sph_harm_ind_list, real_sh_descoteaux_from_index, sph_harm_lookup, lazy_index, SphHarmFit, real_sh_descoteaux, sh_to_rh, forward_sdeconv_mat, SphHarmModel
  from dipy.reconst.utils import _roi_in_volume, _mask_from_roi
  from dipy.direction.peaks import peaks_from_model
  from dipy.core.geometry import vec2vec_rotmat
  from dipy.utils.deprecator import deprecate_with_version, deprecated_params
label_desc: Use image node_id 11 for calling a global function with example usage: auto_response_ssst(gtab, data, roi_center, roi_radii, fa_thr) and returns: response,  ratio