code: def test_qvalues():
      sq2 = np.sqrt(2) / 2.0
      bvals = 1500 * np.ones(7)
      bvals[0] = 0
      bvecs = np.array(
          [
              [0, 0, 0],
              [1, 0, 0],
              [0, 1, 0],
              [0, 0, 1],
              [sq2, sq2, 0],
              [sq2, 0, sq2],
              [0, sq2, sq2],
          ]
      )
      qvals = np.sqrt(bvals / 6) / (2 * np.pi)
      bt = gradient_table(bvals, bvecs, big_delta=8, small_delta=6)
      npt.assert_almost_equal(bt.qvals, qvals)
  
imports: import warnings
  import numpy
  import numpy.testing
  import pytest
  from dipy.data import get_fnames
  from dipy.core.gradients import b0_threshold_empty_gradient_message, b0_threshold_update_slicing_message, gradient_table, GradientTable, gradient_table_from_bvals_bvecs, gradient_table_from_qvals_bvecs, gradient_table_from_gradient_strength_bvecs, WATER_GYROMAGNETIC_RATIO, mask_non_weighted_bvals, orientation_to_string, reorient_bvecs, generate_bvecs, check_multi_b, round_bvals, get_bval_indices, unique_bvals_magnitude, unique_bvals_tolerance, unique_bvals, params_to_btens, btens_to_params, orientation_from_string, reorient_vectors
  from dipy.core.geometry import vec2vec_rotmat, vector_norm
  from dipy.io.gradients import read_bvals_bvecs
  from dipy.utils.deprecator import ExpiredDeprecationError
  from dipy.testing import clear_and_catch_warnings
  from dipy.testing.decorators import set_random_number_generator
label_desc: Use image node_id 12 for calling a global function with example usage: test_qvalues() without return types