Checks whether the element @id exists in the SVG document.
Element IDs should look like an URL fragment identifier; for example, pass
"##foo" (hash <literal>foo</literal>) to get the geometry of the element that
has an <literal>id="foo"</literal> attribute.
An element's id within the SVG, starting with "##" (a single hash
character), for example, "##layer1". This notation corresponds to a URL's
fragment ID.
Checks whether the element @id exists in the SVG document.
Element IDs should look like an URL fragment identifier; for example, pass "##foo" (hash <literal>foo</literal>) to get the geometry of the element that has an <literal>id="foo"</literal> attribute.