def add_file(self, git_path, content):
        """
        Add a new file as blob in the storage and add its tree entry into the index.
        
        :param git_path: str
        :param content: str
        """
        blob_id = self.write_blob(content)
        self.add_index('100644', blob_id, git_path)
Add a new file as blob in the storage and add its tree entry into the index.
        
        :param git_path: str
        :param content: str