"""
review of function

"""

"""
1a. what is function in python
1b. what is function in math
mapping relationship

2. how it works

3. define a function
keyword: def

4. how to use
call a function

5. syntax of function
signature of function
    function name
    function argument
return statement

6. input and output of function

7. function type
built-in function       print(), len(), type(), id()
user-defined function   

8. function arguments
positional argument
default argument
variable argument
    keyword argument
    arbitrary argument   print(*obj) i.e. print(1)  print(2,3)
    
9. Recursive function and recursion
process include itself,  call it in itself
iteration   i.e. for

10. Anonymous function/ lambda function
lambda arg1,[arg2,...] : expr
as a parameter
high order function
filter(func, iterable), map(func, iterable)

11. global scope, local scope, module scope
global variable
local variable
accessibility and visibility

"""