feat: initialize tests, docs and refactor

doc/logging-cookbook.md

@@ -0,0 +1,37 @@
+# Using logging in multiple modules
+
+Multiple calls to `logging.getLogger('someLogger')` return a reference to the
+same logger object. This is true not only within the same module, but also
+across modules as long as it is in the same Python interpreter process. It is
+true for references to the same object; additionally, application code can
+define and configure a parent logger in one module and create (but not
+configure) a child logger in a separate module, and all logger calls to the
+child will pass up to the parent. Here is a main module:
+
+``javascript
+import * as logging from 'eslib/logging';
+import * as my_module from './my_module';
+
+// create logger with 'spam_application'
+var logger = logging.getLogger('spam_application');
+logger.setLevel(logging.DEBUG);
+
+// create file handler which logs even debug messages
+var fh = logging.FileHandler('spam.log')
+fh.setLevel(logging.DEBUG);
+
+// create console handler with a higher log level
+var ch = logging.StreamHandler();
+ch.setLevel(logging.ERROR);
+
+// create formatter and add it to the handlers
+var formatter = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s');
+fh.setFormatter(formatter);
+ch.setFormatter(formatter);
+
+// add the handlers to the logger
+logger.addHandler(fh);
+logger.addHandler(ch);
+
+logger.info('creating an instance of auxiliary_module.Auxiliary')
+```