In [1]: import yt
---------------------------------------------------------------------------
ImportError                               Traceback (most recent call last)
<ipython-input-1-59dfcfe9846c> in <module>()
----> 1 import yt

/Users/molly/yt/yt/__init__.pyc in <module>()
    132
    133 from yt.frontends.api import _frontend_container
--> 134 frontends = _frontend_container()
    135
    136 from yt.frontends.stream.api import \

/Users/molly/yt/yt/frontends/api.pyc in __init__(self)
     51         for frontend in _frontends:
     52             _mod = "yt.frontends.%s.api" % frontend
---> 53             setattr(self, frontend, importlib.import_module(_mod))
     54         setattr(self, 'api', importlib.import_module('yt.frontends.api'))
     55         setattr(self, '__name__', 'yt.frontends.api')

/Users/molly/anaconda2/envs/astroconda/lib/python2.7/importlib/__init__.pyc in import_module(name, package)
     35             level += 1
     36         name = _resolve_name(name[level:], package, level)
---> 37     __import__(name)
     38     return sys.modules[name]

/Users/molly/yt/yt/frontends/ramses/api.py in <module>()
     14 #-----------------------------------------------------------------------------
     15
---> 16 from .data_structures import \
     17       RAMSESDataset
     18

/Users/molly/yt/yt/frontends/ramses/data_structures.py in <module>()
     44 from yt.arraytypes import blankRecordArray
     45
---> 46 from yt.utilities.lib.cosmology_time import \
     47     friedman
     48

ImportError: No module named cosmology_time

In [2]: