Minor fix

fluids/numerics/polynomial_utils.py

@@ -20,14 +20,16 @@
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.
 """
-from math import log, sqrt, comb
+from math import log, sqrt
 
 __all__ = ['polyint', 'polyint_over_x', 'polyder', 'quadratic_from_points',
 'deflate_cubic_real_roots',  'exp_poly_ln_tau_coeffs3', 'exp_poly_ln_tau_coeffs2',
 'polynomial_offset_scale', 'stable_poly_to_unstable',
 'polyint_stable',
 'polyint_over_x_stable',
 ]
+from fluids.numerics.special import comb
+
 
 def stable_poly_to_unstable(coeffs, low, high):
     if high != low: