<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def upload_from_string( self, data, content_type="text/plain", client=None, predefined_acl=None ):
 """Upload contents of this blob from the provided string. .. note:: The effect of uploading to an existing blob depends on the "versioning" and "lifecycle" policies defined on the blob's bucket. In the absence of those policies, upload will overwrite any existing contents. See the `object versioning <https://cloud.google.com/storage/docs/object-versioning>`_ and `lifecycle <https://cloud.google.com/storage/docs/lifecycle>`_ API documents for details. If :attr:`user_project` is set on the bucket, bills the API request to that project. :type data: bytes or str :param data: The data to store in this blob. If the value is text, it will be encoded as UTF-8. :type content_type: str :param content_type: Optional type of content being uploaded. Defaults to ``'text/plain'``. :type client: :class:`~google.cloud.storage.client.Client` or ``NoneType`` :param client: Optional. The client to use. If not passed, falls back to the ``client`` stored on the blob's bucket. :type predefined_acl: str :param predefined_acl: (Optional) predefined access control list """

        data = _to_bytes(data, encoding="utf-8")
        string_buffer = BytesIO(data)
        self.upload_from_file(
            file_obj=string_buffer,
            size=len(data),
            content_type=content_type,
            client=client,
            predefined_acl=predefined_acl,
        )