def initialize_copy(other)
      @unit = other.unit
      @from, @to = other.from, other.to
      @op = other.op.dup
    end
def initialize_copy(other)
      @unit = other.unit
      @from, @to = other.from, other.to
      @op = other.op.dup
    end
Creates a sequence. Typically, it is easier to do it with {Units::Base#sequence},
 like this:

 ```ruby
 TimeMath.day.sequence(from...to)
 ```

 @param unit [Symbol] one of {TimeMath.units};
 @param range [Range] range of time-y values (Time, Date, DateTime);
   note that range with inclusive and exclusive and will produce
   different sequences.

 @private