python - _, 表示什么意思呢

Question

在tensorflow一个学习代码中遇到了这样一行代码：
_, loss_value = sess.run()

想请问一下这个_，表示什么意思呢

Answer 1

Variables that can be ignored

_ Just a placeholder

Answer 2

If you are in REPL, _ can represent the return value of the previous step
For example

>>> (lambda : 2)()
2
>>> _
2

Answer 3

represents the variable name

Answer 4

sess.run() returns two parameters, the first parameter is saved in a variable named _. If _ is printed separately, it represents the value of the latest expression

Answer 5

Indicates variables that will be discarded, crying face

Answer 6

means that func is supposed to return two variables, but you only want to receive the latter variable, so use _ to occupy a position to indicate that it has been received