function interpolateColors(themeColors) {
      var rgbColors = {};

      var hasColorProperty = themeColors.hasOwnProperty('color');

      angular.forEach(themeColors, function (value, key) {
        var color = extractColorOptions(value);
        var hasBackground = key.indexOf('background') > -1;

        rgbColors[key] = parseColor(color);
        if (hasBackground && !hasColorProperty) {
          rgbColors.color = parseColor(color, true);
        }
      });

      return rgbColors;
    }
Convert the color expression into an object with scope-interpolated values
Then calculate the rgba() values based on the theme color parts
@param {Object} themeColors json object, keys are css properties and values are string of
the wanted color, for example: `{color: 'red-A200-0.3'}`.
@return {Object} Hashmap of CSS properties with associated `rgba()` string values