Ruby/Range/Range Extension

class Range
  def each_slow
    x = self.begin
    while x <= self.end
      yield x
      x = x.succ
    end
  end
end
(1..3).each_slow {|x| puts x}
# 1
# 2
# 3

class Range                  # Open an existing class for additions
  def by(step)               # Define an iterator named by
    x = self.begin           # Start at one endpoint of the range
    if exclude_end?          # For ... ranges that exclude the end
      while x < self.end     # Test with the < operator
        yield x
        x += step
      end
    else                     # Otherwise, for .. ranges that include the end
      while x <= self.end    # Test with <= operator
        yield x
        x += step
      end
    end
  end                        # End of method definition
end                          # End of class modification
(0..10).by(2) {|x| print x}  # Prints "0246810"
(0...10).by(2) {|x| print x} # Prints "02468"