 SWIG interface with some variable
declarations in it.

<h2>Manipulating Variables from Python</h2>

Before going any further, it is important to understand some important
differences between C and Python variables.  In C, a variable is
simply a name that refers to a specific location in memory.  For
example, when you declare a global variable '<tt>double a</tt>' you
know that somewhere in memory, 8 bytes have been set aside to hold a
<tt>double</tt> and that <tt>a</tt> is bound to this location for the
lif