\docparam{book\_file}{Help book filename. It is recommended to use this prototype
instead of the one taking URL, because it is less error-prone.}
\docparam{book\_url}{Help book URL (note that syntax of filename and URL is
\docparam{book\_file}{Help book filename. It is recommended to use this prototype
instead of the one taking URL, because it is less error-prone.}
\docparam{book\_url}{Help book URL (note that syntax of filename and URL is