Today, I made quite an impression on my furniture thanks to incessant contact between it and my illustrious head. This, as usual, was due to my looking for a clean regex to solve my issue while working with text files in Vim. My task was, I initially believed, quite simple: delete all the lines that are sandwiched between two types/patterns of lines. In this case, the top slice of the sandwich consisted of a line which was entirely a number and the bottom slice was a line entirely populated with underscores.