cx_Oracle issues

[huw_at1]

Hey all. When using cx_Oracle to run a procedure like:

cursor.execute("select (obj.function(value)) from table where
id=blah")

I am getting the following error:

ORA-06502: PL/SQL: numeric or value error: character string buffer too
small ORA-06512: at line 1

Looking at cursor.description I get:

[('(obj.function(value))', <type 'cx_Oracle.STRING'>, 4000, 4000, 0,
0, 1)]

Any tips - i have never seen this error before but am guessing that
the value being returned is too big for the buffer size set for the
cursor. the procedure fetches data from a LOB.

Any suggestions/confirmations?

Many thanks