The Base64 encoded content of the attachment

        :param value: The Base64 encoded content of the attachment
        :type value: FileContent, string

def file_content(self, value):
        """The Base64 encoded content of the attachment

        :param value: The Base64 encoded content of the attachment
        :type value: FileContent, string
        """
        if isinstance(value, FileContent):
            self._file_content = value
        else:
            self._file_content = FileContent(value)