diff --git a/weboob/bcall.py b/weboob/bcall.py
index 476cc39b..727c9ef7 100644
--- a/weboob/bcall.py
+++ b/weboob/bcall.py
@@ -31,6 +31,9 @@ class CallErrors(Exception):
         Exception.__init__(self, "Several errors have been raised:\n%s" % ('\n'.join(['%s: %s' % (b, e) for b, e in errors])))
         self.errors = copy(errors)
 
+    def __iter__(self):
+        return self.errors.__iter__()
+
 class Result(object):
     def __init__(self, backend, result):
         self.backend = backend
@@ -48,6 +51,11 @@ class Result(object):
 
 class BackendsCall(object):
     def __init__(self, backends, function, *args, **kwargs):
+        """
+        @param backends  list of backends to call
+        @param function  backends' method name, or callable object
+        @param args, kwargs  arguments given to called functions
+        """
         # Store if a backend is finished
         self.backends = {}
         for backend in backends:
@@ -69,9 +77,9 @@ class BackendsCall(object):
         with self.mutex:
             for b in backends:
                 debug('New timer for %s' % b)
-                self.threads.append(Timer(0, self.caller, (b, function, args, kwargs)).start())
+                self.threads.append(Timer(0, self._caller, (b, function, args, kwargs)).start())
 
-    def caller(self, b, function, args, kwargs):
+    def _caller(self, b, function, args, kwargs):
         debug('Hello from timer %s' % b)
         with b:
             try:
diff --git a/weboob/ouiboube.py b/weboob/ouiboube.py
index e6530915..49bfaffd 100644
--- a/weboob/ouiboube.py
+++ b/weboob/ouiboube.py
@@ -93,16 +93,48 @@ class Weboob(object):
         return self.backends
 
     def iter_backends(self, caps=None):
+        """
+        Iter on each backends.
+
+        Note: each backend is locked when it is returned.
+
+        @param caps  Optional list of capabilities to select backends
+        @return  iterator on selected backends.
+        """
         for name, backend in self.backends.iteritems():
             if caps is None or backend.has_caps(caps):
                 with backend:
                     yield backend
 
     def do(self, function, *args, **kwargs):
+        """
+        Do calls on loaded backends with specified arguments, in separated
+        threads.
+
+        This function has two modes:
+        - If 'function' is a string, it calls the method with this name on
+          each backends with the specified arguments;
+        - If 'function' is a callable, it calls it in a separated thread with
+          the locked backend instance at first arguments, and *args and
+          **kwargs.
+
+        @param function  backend's method name, or callable object
+        @return  an iterator of results
+        """
         backends = [b for b in self.iter_backends()]
         return BackendsCall(backends, function, *args, **kwargs)
 
     def do_caps(self, caps, function, *args, **kwargs):
+        """
+        Do calls on loaded modules with the specified capabilities, in
+        separated threads.
+
+        See also documentation of the 'do' method.
+
+        @param caps  list of caps or cap to select backends
+        @param function  backend's method name, or callable object
+        @return  an iterator of results
+        """
         backends = [b for b in self.iter_backends(caps)]
         return BackendsCall(backends, function, *args, **kwargs)