revereted two files

Author: pavelkomarov

pynumdiff/finite_difference/_finite_difference.py

@@ -1,5 +1,6 @@
 import numpy as np
 from pynumdiff.utils import utility
+from warnings import warn
 
 
 def first_order(x, dt, params=None, options={}, num_iterations=None):

pynumdiff/linear_model/_linear_model.py

@@ -1,5 +1,6 @@
 import copy, math, logging, scipy
 import numpy as np
+from warnings import warn
 
 from pynumdiff import smooth_finite_difference
 from pynumdiff.finite_difference import first_order as finite_difference