def expansion_attribute(styles={})
      return nil if styles.nil?
      return nil if styles[:expansion].nil?
      value = styles[:expansion]
      return 0 if [0, :default].include?(value)
      return nil unless value.respond_to?(:to_f)
      return value.to_f
    end
def expansion_attribute(styles={})
      return nil if styles.nil?
      return nil if styles[:expansion].nil?
      value = styles[:expansion]
      return 0 if [0, :default].include?(value)
      return nil unless value.respond_to?(:to_f)
      return value.to_f
    end
NSExpansionAttributeName

 :expansion
   * 0, :default
   * A Float