workers: add explicit process to base class

As per https://docs.python.org/3/library/exceptions.html#NotImplementedError

> In user defined base classes, abstract methods should raise this
exception when they require derived classes to override the method
[...].

1 files changed, 6 insertions, 0 deletions

diff --git a/python/sandcrawler/workers.py b/python/sandcrawler/workers.py
index c290421..54bd581 100644
--- a/python/sandcrawler/workers.py
+++ b/python/sandcrawler/workers.py
@@ -52,6 +52,12 @@ class SandcrawlerWorker(object):
         print("Worker: {}".format(self.counts), file=sys.stderr)
         return self.counts
 
+    def process(self, task):
+        """
+        Derived workers need to implement business logic here.
+        """
+        raise NotImplementedError('implementation required')
+
 class MultiprocessWrapper(SandcrawlerWorker):
 
     def __init__(self, worker, sink, jobs=None):