What is the meaning of using a wildcard as an argument in subprocess popen?

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Using a wildcard as an argument in subprocess popen allows the command to operate on a group of files that match a certain pattern. For example, if you use "*.txt" as a wildcard, the command will operate on all files in the current directory that end in ".txt". This can be useful when you need to process a large number of files that have a common naming pattern.