Functions and Built-in Functions
Function: All functions start with reserved keyword 'def' All functions' definition ends with ':' By convention, indentation in Python is 4 spaces To write a comment, use '#' Every function returns a value. If there is no return statement, Python will return the special value None Note: print('hello ' + 'Huy') is the same as print('hello', 'Huy') def bye(): print('Goodbye') # print Goodbye and None