push_text_message Push a simple text message to a user via LINE. Inputs: user_id (string?): The user ID to receive a message. Defaults to DESTINATION_USER_ID. message.text (string): The plain text content to send to the user. push_flex_message Push a highly customizable flex message to a user via LINE. Inputs: user_id (string?): The user ID to receive a message. Defaults to DESTINATION_USER_ID. me