code: def _calc_h(cosang, stiffness=4, n_legendre_terms=50):
      """Calculate spherical spline h function between points on a sphere.
  
      Parameters
      ----------
      cosang : array-like | float
          cosine of angles between pairs of points on a spherical surface. This
          is equivalent to the dot product of unit vectors.
      stiffness : float
          stiffnes of the spline. Also referred to as ``m``.
      n_legendre_terms : int
          number of Legendre terms to evaluate.
      """
      factors = [
          (2 * n + 1)
          / (
              n ** (stiffness - 1)
              * (n + 1) ** (stiffness - 1)
              * 4
              * np.pi
          )
          for n in range(1, n_legendre_terms + 1)
      ]
      return legval(cosang, [0] + factors)
  
imports: import numpy
  from numpy.polynomial.legendre import legval
  from scipy.interpolate import RectBivariateSpline
  from scipy.linalg import pinv
  from scipy.spatial.distance import pdist, squareform
  from .._fiff.meas_info import _simplify_info
  from .._fiff.pick import pick_channels, pick_info, pick_types
  from ..surface import _normalize_vectors
  from ..utils import _validate_type, logger, verbose, warn
label_desc: Use image node_id 1 for calling a global function with example usage: _calc_h(cosang, stiffness, n_legendre_terms) and returns: legval