<h3>intersection function</h3>
Returns a geometry that represents the shared portion of geometry a and geometry b.

<h4>Syntax</h4>
<pre>intersection( geometry a , geometry b)</pre>

<h4>Arguments</h4>
geometry &rarr; geometry
geometry &rarr; geometry

<h4>Example</h4>
<pre> geomToWKT( intersection( geomFromWKT( 'LINESTRING(3 3 , 4 4 , 5 5)' ) , geomFromWKT( 'LINESTRING(3 3 , 4 4 )' ))  )   &rarr; returns LINESTRING(3 3, 4 4)</pre>