fix warning

sedkit/spectrum.py

@@ -23,7 +23,7 @@
 import numpy as np
 from pandas import DataFrame
 from svo_filters import Filter
-
+import warnings
 
 from . import mcmc as mc
 from . import utilities as u
@@ -1494,7 +1494,11 @@ def __init__(self, file, wave_units=None, flux_units=None, ext=0,
 
         # Sanity check for wave_units
         if data[0].min() > 100 and wave_units == q.um:
-            print("WARNING: Your wavelength range ({} - {}) looks like Angstroms. Are you sure it's {}?".format(data[0].min(), data[0].max(), wave_units))
+            msg = (
+                f"Your wavelength range ({data[0].min()} - {data[0].max()})"
+                f"looks like Angstroms. Are you sure it's {wave_units}?"
+            )
+            warnings.warn(msg)
 
         # Apply units
         wave = data[0] * wave_units