Build, test, and debug regular expressions
Matches text at the beginning of a line that starts with the literal prefix 'STR_' followed by zero or more non-underscore characters. The multiline flag makes the caret anchor to the start of each line, while the global flag finds all matches. It's commonly used to locate string constant names like STR_DELIVERY in source code, capturing the prefix and the following identifier segment up to the next underscore.