Add FissionProductYields class and Decay class

docs/source/conf.py

@@ -25,7 +25,7 @@ except ImportError:
 
 
 MOCK_MODULES = ['numpy', 'numpy.polynomial', 'numpy.polynomial.polynomial',
-                'h5py', 'pandas', 'opencg']
+                'h5py', 'pandas', 'uncertainties', 'opencg']
 sys.modules.update((mod_name, MagicMock()) for mod_name in MOCK_MODULES)
 
 import numpy as np

docs/source/pythonapi/index.rst

@@ -373,6 +373,8 @@ Core Classes
     openmc.data.CoherentElastic
     openmc.data.FissionEnergyRelease
     openmc.data.DataLibrary
+    openmc.data.Decay
+    openmc.data.FissionProductYields
 
 Core Functions
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