How does assign_vertex_id() in pgRouting work?

I'm trying to follow this tutorial,

http://www.pgrouting.org/docs/foss4g2008/ch06.html

but on the step with assign_vertex_id() it shows an error for executing the SQL query:

SQL error:

ERROR:  column "’ways’" does not exist
LINE 1: SELECT assign_vertex_id(’ways’, 0.00001, ’the_geom’, ’gid’);
                            ^
In statement:
SELECT assign_vertex_id(’ways’, 0.00001, ’the_geom’, ’gid’);

I have not found any documentation or forums regarding how assign_vertex_id() should actually work.

The only thing that I know is that the first parameter should be a table_name and not a column name.