This change is an attempt to handle gosimple linter finfings in order to
make the code easier to follow. It includes the following changes:
- use strings.Contains instead of strings.Index != -1
- use time.Since which is the standard library helper. See https://github.com/golang/go/blob/go1.15.2/src/time/time.go#L866-L867
- remove unneeded return statements at the end of methods
- preallocate maps when their capacity is known
- avoid underscoring values when they can be omitted
- avoid fmt.Sprintf() calls when the only argument is already a string
Signed-off-by: Miguel Ángel Jimeno <miguelangel4b@gmail.com>