Adding version check

AllenDowney · AllenDowney · commit a43bdf6b504f · 2017-10-27T13:04:49.000-04:00
diff --git a/code/modsim.py b/code/modsim.py
@@ -6,26 +6,29 @@
 License: https://creativecommons.org/licenses/by/4.0)
 """
 
-#TODO: check that we have at least version 3.6
-
-import inspect
-
 import logging
 logger = logging.getLogger(name='modsim.py')
 
+# make sure we have Python 3.6 or better
+import sys
+if sys.version_info < (3, 6):
+    logger.warn('modsim.py depends on Python 3.6 features.')
+
+import inspect
 import matplotlib.pyplot as plt
 import numpy as np
 import pandas as pd
+import scipy
+import sympy
 
 import seaborn as sns
 sns.set(style='white', font_scale=1.5)
 
-import scipy
-import sympy
 import pint
 UNITS = pint.UnitRegistry()
 Quantity = UNITS.Quantity
 
+# expose some names so we can use them without dot notation
 from copy import copy
 from numpy import sqrt, log, exp, pi
 from pandas import DataFrame, Series
@@ -37,7 +40,6 @@
 from scipy.optimize import minimize_scalar
 
 
-
 def linspace(start, stop, num=50, **kwargs):
     """Returns an array of evenly-spaced values in the interval [start, stop].
     
