environment/lib/python2.7/site-packages/nose/util.py
def src(filename):
    """Find the python source file for a .pyc, .pyo or $py.class file on
    jython. Returns the filename provided if it is not a python source
    file.
    """
    if filename is None:
        return filename
    if sys.platform.startswith('java') and filename.endswith('$py.class'):
        return '.'.join((filename[:-9], 'py'))
    base, ext = os.path.splitext(filename)
    if ext in ('.pyc', '.pyo', '.py'):
        return '.'.join((base, 'py'))
    return filename
def src(filename):
    """Find the python source file for a .pyc, .pyo or $py.class file on
    jython. Returns the filename provided if it is not a python source
    file.
    """
    if filename is None:
        return filename
    if sys.platform.startswith('java') and filename.endswith('$py.class'):
        return '.'.join((filename[:-9], 'py'))
    base, ext = os.path.splitext(filename)
    if ext in ('.pyc', '.pyo', '.py'):
        return '.'.join((base, 'py'))
    return filename
Find the python source file for a .pyc, .pyo or $py.class file on
    jython. Returns the filename provided if it is not a python source
    file.