pump step function used to pass data from the
server to the sink. Defaults to the LTN12 <tt>pump.step</tt> function;
<li><tt>create</tt>: An optional function to be used instead of
<a href=tcp.html#socket.tcp><tt>socket.tcp</tt></a> when the communications socket is created. 
</ul>

<p class=return>
If successful, the simple version returns the URL  contents as a
string, and the generic function returns 1.  In case of error,  both
functions return <b><tt>nil</tt></b> and an error message describing the
erro