def initialize(options={})
      # defaults
      @formula1 = @formula2 = @error = @errorTitle = @operator = @prompt = @promptTitle = @sqref = nil
      @allowBlank = @showErrorMessage = true
      @showDropDown = @showInputMessage = false
      @type = :none
      @errorStyle = :stop
      parse_options options
    end
Creates a new {DataValidation} object
@option options [String] formula1
@option options [String] formula2
@option options [Boolean] allowBlank - A boolean value indicating whether the data validation allows the use of empty or blank entries.
@option options [String] error - Message text of error alert.
@option options [Symbol] errorStyle - The style of error alert used for this data validation.
@option options [String] errorTitle - itle bar text of error alert.
@option options [Symbol] operator - The relational operator used with this data validation.
@option options [String] prompt - Message text of input prompt.
@option options [String] promptTitle - Title bar text of input prompt.
@option options [Boolean] showDropDown - A boolean value indicating whether to display a dropdown combo box for a list type data validation
@option options [Boolean] showErrorMessage - A boolean value indicating whether to display the error alert message when an invalid value has been entered, according to the criteria specified.
@option options [Boolean] showInputMessage - A boolean value indicating whether to display the input prompt message.
@option options [String] sqref - Range over which data validation is applied, in "A1:B2" format.
@option options [Symbol] type - The type of data validation.