Python underscore as a function parameter

identifier, metasyntactic-variable, parameters, python

Solution

From what I've been able to figure out, it seems like this is the case:

`_` is used to indicate that the input variable is a throwaway variable/parameter and thus might be required or expected, but will not be used in the code following it.

For example:

# Ignore a value of specific location/index 
for _ in range(10) 
    print("Test")
  
# Ignore a value when unpacking 
a,b,_,_ = my_method(var1)

(Credit to this post)

The specific example I came across was this:

    def f(_):
        x = random() * 2 - 1
        y = random() * 2 - 1
        return 1 if x ** 2 + y ** 2 < 1 else 0

Problem

I have a python specific question. What does a single underscore `_` as a parameter means? I have a function calling `hexdump(_)`. The _ was never defined, so I guess it has some special value, I could not find a reference telling me what it means on the net. I would be happy if you could tell me.

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