'Returns a version string for the resource at the given path.
This class method may be overridden by subclasses.  The
default implementation is a hash of the file\'s contents.
.. versionadded:: 3.1'

@classmethod
def get_content_version(cls, abspath):

    data = cls.get_content(abspath)
    hasher = hashlib.md5()
    if isinstance(data, bytes):
        hasher.update(data)
    else:
        for chunk in data:
            hasher.update(chunk)
    return hasher.hexdigest()
