:param category: audio|image|office|text|video
        :param extension: file extension
        :param depth: depth of the file (depth >= 0)

def file_path(self, depth=1, category=None, extension=None):
        """
        :param category: audio|image|office|text|video
        :param extension: file extension
        :param depth: depth of the file (depth >= 0)
        """
        file = self.file_name(category, extension)
        path = "/{0}".format(file)
        for _ in range(0, depth):
            path = "/{0}{1}".format(self.generator.word(), path)
        return path