def METHOD_NAME(self, attachments):
    """
    Two types of attachments can be attached to emails:
        * "Content" attachment is one of:
            * instance of ``MIMEBase`` (from ``email.mime.base``);
            * list ``[filename, content, mimetype]``;
        * "File" attachment is a path to file from an instance of
          ``FileField`` based fields.
    "Content" and "file" attachments attached to emails differently.
    """
    content_attachments = []
    file_attachments = []
    if attachments is not None:
        for attachment in attachments:
            if isinstance(attachment, str):
                file_attachments.append(attachment)
            else:
                content_attachments.append(attachment)
    return content_attachments, file_attachments