# File lib/core/facets/array/rotate.rb, line 35
    def rotate!(n=1)
      n = n.to_int
      return self if (n == 0 or self.empty?)
      if n < 0
        n.abs.times{ self.unshift( self.pop ) }
      else
        n.abs.times{ self.push( self.shift ) }
      end
      self
    end