docs: def set_padist_gaussian_loss_cone(self, boundary_rad, expwidth):
          """Set the pitch-angle distribution to a Gaussian loss cone.
  
          **Call signature**
  
          *boundary_rad*
            The angle inside which there are no losses, in radians.
          *expwidth*
            The characteristic width of the Gaussian loss profile
            *in direction-cosine units*.
          Returns
            *self* for convenience in chaining.
  
          See ``OnlineI.pdf`` in the Supplementary Data for a precise
          definition. (And note the distinction between α_c and μ_c since not
          everything is direction cosines.)
  
          """
          self.in_vals[IN_VAL_PADIST] = PADIST_GLC
          self.in_vals[IN_VAL_LCBDY] = boundary_rad * 180 / np.pi # rad => deg
          self.in_vals[IN_VAL_DELTAMU] = expwidth
          return self