I'm a big proponent of self-documenting, readable code. This is being reinforced now that I'm reading "Clean Code" (Robert C. Martin). I think it's a good habit to use descriptive variable names. E.g., 'activity' vs 'a'. Even though it's a short function and readability isn't significantly affected by using 'a' as a variable name, it seems overall better to use a more descriptive name.