pe: Number,
                value: 0
            },

            _glyphCount: {
                type: Number,
                value: 0
            }
        },

        _getGlyphCount: function (str) {
            var glyphs = [];

            str.split('').forEach(function (value) {
                if (glyphs.indexOf(value) === -1) {
                    glyphs.push(value);
                }
            });

            return glyphs.join('').length;
        },

        valueChanged: function (newValue, old