code: func (s Linear) ebase() int {
  	if s.Base == 0 {
  		return 10
  	} else if s.Base == 1 {
  		panic("scale.Linear cannot have a base of 1")
  	} else if s.Base < 0 {
  		panic("scale.Linear cannot have a negative base")
  	}
  	return s.Base
  }
docs: // ebase sanity checks and returns the "effective base" of this scale.
  // If s.Base is 0, it returns 10. If s.Base is 1 or negative, it
  // panics.