def _validate_path(path):
  """Basic validation of Google Storage paths.

  Args:
    path: a Google Storage path. It should have form '/bucket/filename'
      or '/bucket'.

  Raises:
    ValueError: if path is invalid.
    TypeError: if path is not of type basestring.
  """
  if not path:
    raise ValueError('Path is empty')
  if not isinstance(path, basestring):
    raise TypeError('Path should be a string but is %s (%s).' %
                    (path.__class__, path))