end_of_month

# File activesupport/lib/active_support/core_ext/time/calculations.rb, line 242
  def end_of_month
    #self - ((self.mday-1).days + self.seconds_since_midnight)
    last_day = ::Time.days_in_month(month, year)
    change(:day => last_day, :hour => 23, :min => 59, :sec => 59, :usec => Rational(999999999, 1000))
  end