Add cli logging example

Author: gjbex

Diff for: source-code/command-line-arguments/Fire/README.md

@@ -6,5 +6,7 @@ applications with a command line interface.
 ## What is it?
 
 1. `calculator.py`/`calculations.py`: Calculator application that
-   implements addition and multiplication.
+   implements addition, substraction,  multiplication and division.
 1. `sayer.py`: Illustration of grouped commands.
+1. `cl_logger.py`/`log_management.py`/`log_operations.py`: logging
+   from the command line example.

Diff for: source-code/command-line-arguments/Fire/cl_logger.py

@@ -0,0 +1,8 @@
+#!/usr/bin/env python
+
+import fire
+import log_operations
+
+
+if __name__ == '__main__':
+    fire.Fire(log_operations)

Diff for: source-code/command-line-arguments/Fire/log_management.py

@@ -0,0 +1,12 @@
+import re
+
+
+def create(file_name):
+    with open('.cl_logger.txt', 'w') as file:
+        print(f'file = {file_name}', file=file)
+
+def _get_log_file():
+    with open('.cl_logger.txt', 'r') as file:
+        for line in file:
+            if match := re.match('file = (.+)', line):
+                return match[1]

Diff for: source-code/command-line-arguments/Fire/log_operations.py

@@ -0,0 +1,17 @@
+from datetime import datetime as _datetime
+from log_management import _get_log_file, create
+
+
+def _log(level, msg):
+    time = _datetime.strftime(_datetime.now(), '%Y-%d-%m %H:%M:%S')
+    with open(_get_log_file(), 'a') as file:
+        print(f'{time} [{level}]: {msg}', file=file)
+
+def error(msg):
+    _log('error', msg)
+    
+def warning(msg):
+    _log('warning', msg)
+
+def info(msg):
+    _log('info', msg)