Start rename of BLATHER -> TRACE

This appears to be standardizing around the name
TRACE instead of BLATHER so start to move taskflow
internally to use this name instead.

Change-Id: I095039ac556eb07b821a29528b1b76651bcbab5c

taskflow/logging.py

@@ -20,11 +20,14 @@ import logging
 
 _BASE = __name__.split(".", 1)[0]
 
-# Add a BLATHER level, this matches the multiprocessing utils.py module (and
+# Add a BLATHER/TRACE level, this matches the multiprocessing
-# kazoo and others) that declares a similar level, this level is for
+# utils.py module (and oslo.log, kazoo and others) that declares a similar
-# information that is even lower level than regular DEBUG and gives out so
+# level, this level is for information that is even lower level than regular
-# much runtime information that it is only useful by low-level/certain users...
+# DEBUG and gives out so much runtime information that it is only
+# useful by low-level/certain users...
 BLATHER = 5
+TRACE = BLATHER
+
 
 # Copy over *select* attributes to make it easy to use this module.
 CRITICAL = logging.CRITICAL
@@ -43,6 +46,10 @@ class _BlatherLoggerAdapter(logging.LoggerAdapter):
         """Delegate a blather call to the underlying logger."""
         self.log(BLATHER, msg, *args, **kwargs)
 
+    def trace(self, msg, *args, **kwargs):
+        """Delegate a trace call to the underlying logger."""
+        self.log(TRACE, msg, *args, **kwargs)
+
     def warn(self, msg, *args, **kwargs):
         """Delegate a warning call to the underlying logger."""
         self.warning(msg, *args, **kwargs)