defnot_empty:

Returns and len(s .strip())>；) >; 0

#returnsands. Strip ()

# If you write S directly. Strip () Then if s is None, an error will be reported, because None has no strip method.

# If s is None, then any value of None and is False, and directly returns false.

# If s is not None, determine s.. Whether trip () is empty.

In this way, the filter can filter out values such as "none" and "and".

Look at it in two parts. The first part is to sort the length. Equivalent to range(5), and his result is. 0 1234。 The second part is the specific sorting rules. The sorting rule is to sort by the value of nums. If it is not declared, reverse is the default ascending order. It is a range(5) array, sorted by the values of nums(0 to 4), and returned according to this result.

Python must recite the content:

1, variable. Refers to variables in the process of program execution. Defining a variable will be accompanied by three characteristics, namely, memory ID, data type and variable value. Constant refers to the constant quantity in the process of program execution. Constants are usually defined in capital letters.

2. Interact with the program. In ancient times, when we went to the bank to withdraw money, we needed a bank clerk to wait for us to input our account password to him, then he would verify it, and then we would input the withdrawal amount and tell him.

Proud modern people will provide customers with an ATM machine to interact with users, thus replacing manpower. However, the machine is dead, and we must write a program to make it run, which requires a mechanism in our programming language to interact with users and receive data input by users.