code: function extractColorOptions(expression) {
        var parts = expression.split('-');
        var hasTheme = angular.isDefined($mdTheming.THEMES[parts[0]]);
        var theme = hasTheme ? parts.splice(0, 1)[0] : $mdTheming.defaultTheme();
  
        return {
          theme: theme,
          palette: extractPalette(parts, theme),
          hue: extractHue(parts, theme),
          opacity: parts[2] || 1
        };
      }
docs: For the evaluated expression, extract the color parts into a hash map
  @param {string} expression color expression like 'red-800', 'red-A200-0.3',
  'myTheme-primary', or 'myTheme-primary-400'
  @returns {{hue: *, theme: any, palette: *, opacity: (*|string|number)}}