def _fs_home_problem(fs_home):
    if fs_home is None:
        return "FREESURFER_HOME is not set."
    elif not os.path.exists(fs_home):
        return "FREESURFER_HOME (%s) does not exist." % fs_home
    else:
        test_dir = os.path.join(fs_home, 'subjects', 'fsaverage')
        if not os.path.exists(test_dir):
            return ("FREESURFER_HOME (%s) does not contain the fsaverage "
                    "subject." % fs_home)
Remove the source files from this requirement, if they are marked
dataset/ETHPy150Open mne-tools/mne-python/mne/gui/_file_traits.py/_fs_home_problem--crossover with--dataset/ETHPy150Open balanced/status.balancedpayments.com/venv/lib/python2.7/site-packages/pip-1.3.1-py2.7.egg/pip/req.py/InstallRequirement.remove_temporary_source