You quoted the title, but the title isn't the complete conclusion, which is: > As such, software developers should be wary of breaking their code into too smal

You quoted the title, but the title isn't the complete conclusion, which is: > As such, software developers should be wary of breaking their code into too small pieces, and actively avoid introducing very short (1-3 lines) functions when given the choice. At the very least unnecessary single-line functions (ie. excluding getters, setters etc.) should be all but banned. I believe a x_to_y(x) fits into the "etc." of acceptable single-line functions.