keywords in python
=================
==> pre-defined words
	which have a specific meaning
==> are also called as "reserved words".
==> total of 35 keywords in python.
==> for the keywords there is a module (pre-defined) with the name "keyword" in python library
an identifier to identify all 35 keywords from "keyword" module "kwlist"

ex:
# to find the smallest among two numbers
a = 97
b = 79

if a < b:
	small = a
else:
	small = b

================================

# WRITE A PYTHON PROGRAM TO LIST AND DISPLAY ALL AVAILABLE KEYWORDS.

import keyword

keyword_list = keyword.kwlist   # listing all the available keywords

print(keyword_list)     # printing of all the available keywords as a group.


['False', 'None', 'True', 'and', 'as', 'assert', 'async', 'await', 'break', 'class', 'continue', 'def', 'del', 
'elif', 'else', 'except', 'finally', 'for', 'from', 'global', 'if', 'import', 'in', 'is', 'lambda', 'nonlocal', 'not', 'or', 
'pass', 'raise', 'return', 'try', 'while', 'with', 'yield']

=====================================================================

COMMENTS IN PYTHON
====================

==> most valuable part of the program
==> the comments are some extra-lines of our program
	which are not to be executed.
==> comments can be used for the "documentation". it can be useful for the reading purpose.
==> to add the description about the program ==> comments are used.
==> COMMENTS CAN BE ALLOWED TO ADD IN ANYWHERE OF THE PROGRAM.
==> two ways to write comments:
	1) using # ==> the comments can be within the same line. (single line comments)
	2) using triple quotes ==> when the comments in multiple lines

# WRITE A PYTHON PROGRAM TO LIST AND DISPLAY ALL AVAILABLE KEYWORDS.

import keyword

# keyword_list = keyword.kwlist  listing all the available keywords
#
# print(keyword_list)   printing of all the available keywords as a group.

print(keyword.kwlist)

"""
    first approach:
        1. we need to import the keyword module from python library using "import" keyword.
        2. we required to prepare all the keywords as group using 'kwlist' is an identifier and 'keyword' is a module.
        3. print that required or prepared group using print()
"""

'''
    second approach:
        1. we need to import the keyword module from python library using "import" keyword.
        2. we should create all keywords as a group and print that group using print()
'''
============================================================

IDENTIFIERS IN PYTHON
=====================
==> WHEN WE REQUIRED TO NAME ANY ENTITY IN THE PROGRAM, WE USED "IDENTIFIERS".
HERE, ENTITIES OF PROGRAM ARE:
	VARIABLES ==> FOR THE DATA STORAGE.
	FUNCTIONS ==> MODULAR APPROACH 
	CLASS ==> 
	OBJECT, METHODS, MODULES, PYTHON FILE ETC.

RULES FOR AN IDENTIFIERS:'
=========================
1) THE ALLOWED CHARACTERS:
	alphabets ==> upper case/lower case/both
	digits ==> 0 to 9
	only one special character ==> _ (underscore)
ex: ravi_27, python, etc ==> valid identifiers

2) THE IDENTIFIER SHOULD NEVER START WITH DIGIT.
EX: 97abc, 123ravi etc. ==> invalid
Note:
	if the identifier with the digit at the beginning ==> Syntax Error
Note:
	if the idnetifier with underscore at the start ==> valid

3) THE IDENTIIFER NEVER BE INCLUDE WITH SPACE.
Note: if an identifier  with space ==> Syntax Error.

4) THE IDENTIFER NEVER ALLOWED WITH ANY OTHER SPECIAL CHARACTERS.
Note: if an identifier with a special character ==> Syntax Error.

5) IDENTIFERS ARE CASE SENSITIVE.
EX: A NAME WITH LOWER CASE AND SAME NAME WITH UPPER CASE, BOTH ARE CONSIDERED BY THE INTERPRETER AS DIFFERENT.
ex: abc = 100
ABC = 200

6) NO LIMIT IN LENGTH OF AN IDENTIIFER.

abc = 100   # valid identifier
abc_123 = 1000
# 123abc = 10000
_123 = 10000
_abc = 9797
# python program = 121212
# abc@12 = 1234565
Abc = 1212
ABC = 2121

AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA = 123456789

print(_123)

print(abc)
print(abc_123)
# print(123abc)
print(_abc)
# print(python program)
# print(abc@12)

print(Abc)
print(ABC)
print(AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA)

==================================================

ASSIGNMENT
===========
IDENTIFY THE VALID AND INVALID IDENTIFIERS AND MENTION THE REASON.

rateofInterest
rate@123
python
c#
c++
java
sbiloanrate
myClass
class_1212
1_class

=====================================================

IO OPERATIONS
==============
==> IO ==> INPUT AND OUTPUT OPERATIONS
INPUT ==> READING A VALUE
	==> TAKING THE VALUE FROM THE KEYWORD.
	==> input()

OUTPUT ==> WRITING A VALUE
	==> DISPLAY ANYTHING ON THE SCREEN
	print()