How to use the artifacts.source_type.PathSourceType function in artifacts

def testInitialize(self):
    """Tests the __init__ function."""
    source_type.PathSourceType(paths=[u'test'])
    source_type.PathSourceType(paths=[u'test'], separator=u'\\')

def testInitialize(self):
    """Tests the __init__ function."""
    source_type.PathSourceType(paths=[u'test'])
    source_type.PathSourceType(paths=[u'test'], separator=u'\\')

"""Initializes a source type.

    Args:
      paths (Optional[str]): paths relative to the root of the file system.
      separator (Optional[str]): path segment separator.

    Raises:
      FormatError: when paths is not set or not a list type.
    """
    if not paths:
      raise errors.FormatError('Missing paths value.')

    if not isinstance(paths, list):
      raise errors.FormatError('Invalid paths value, not a list.')

    super(PathSourceType, self).__init__()
    self.paths = paths
    self.separator = separator