def get_command(message, prefixes):
    """
    Gets a command (first word after the prefix) and stores it in the message
    :param message: MessageWrapper to extract from
    :param prefixes: list of valid prefixes or string of valid prefix
    :return: command name
    """
    args = message.content.split(' ')
    if isinstance(prefixes, list):
        for sign in prefixes:
            if message.content.startswith(sign):
                message.prefix = sign
                message.command = (args[0])[len(sign):]
                return message.command
    elif isinstance(prefixes, str):
        if message.content.startswith(prefixes):
            message.prefix = prefixes
            message.command = (args[0])[len(prefixes):]
            return message.command
    return None