Fix order of imports

tupak/gw/conversion.py

@@ -2,6 +2,9 @@ from __future__ import division
 import tupak
 import numpy as np
 import pandas as pd
+
+from tupak.core.utils import logger
+
 try:
     from astropy.cosmology import z_at_value, Planck15
     import astropy.units as u
@@ -9,8 +12,6 @@ except ImportError:
     logger.warning("You do not have astropy installed currently. You will "
                     " not be able to use some of the prebuilt functions.")
 
-from tupak.core.utils import logger
-
 try:
     import lalsimulation as lalsim
 except ImportError: