How to declare a good variable name in programming.

1.What is a variable
A variable can be a empty container in which we can store some data.

2.Points to remember while declaring a variable

• The variable name may start with a underscore or a letter.

• It can not start with a digit or a symbol. For example-7,4,%,!,?,etc.

• Variable can only contain letters, underscores, or a digit after a digit. For example-a=10
  a_2=12,etc.
  3.Examples
  1.
  

num1_list1=['science', 'history', 'mathematics']
print(num1_list1)

Output:
['science', 'history', 'mathematics']

2.

_123=("dev community")
print(_123)

Output:
dev community

3.

foo="Hello"
print(foo)

Output:
Hello

4.

my_tuple = (1, 2, 3, 4)
print (len(my_tuple))

Output:
4