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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def getSelectedTemplateCSS(self):
 """Looks for the CSS file from the selected template and return its contents. If the selected template is default.pt, looks for a file named default.css in the stickers path and return its contents. If no CSS file found, retrns an empty string """

        template = self.getSelectedTemplate()
        # Look for the CSS
        content = ""
        if template.find(":") >= 0:
            # A template from another add-on
            prefix, template = template.split(":")
            templates_dir = self._getStickersTemplatesDirectory(prefix)
            css = "{0}.css".format(template[:-3])
            if css in os.listdir(templates_dir):
                path = "%s/%s.css" % (templates_dir, template[:-3])
                if os.path.isfile(path):
                    with open(path, "r") as content_file:
                        content = content_file.read()
        else:
            this_dir = os.path.dirname(os.path.abspath(__file__))
            templates_dir = os.path.join(this_dir, "templates/stickers/")
            # Only use the directory asked in "filter_by_type"
            if self.filter_by_type:
                templates_dir = templates_dir + "/" + self.filter_by_type
            path = "%s/%s.css" % (templates_dir, template[:-3])
            if os.path.isfile(path):
                with open(path, "r") as content_file:
                    content = content_file.read()
        return content