Co-authored-by: Averi Kitsch <akitsch@google.com>

1. Moved "instance id", "database", and "table" values initiation after the "Automatically restart kernel after installs" cell to retain variable values after restart.

2. Adding missing - sign to package install code

3. Set-up GOOGLE_CLOUD_PROJECT env variable, it is needed in the document loader function

…ace (#104)

* feat(graph): add Spanner Graph support to LangChain GraphStore interface

1) Add SpannerGraphStore implementation of GraphStore;
2) Add an integration test;
3) Add a notebook to demonstrate the usage;
4) Misc updates: requirements, __init__

* Allow more flexible input that can generated by LLMs

1) same edge label between different types of nodes

E.g.

Company FOCUS_ON Product
Company FOCUS_ON Technology

2) the same doc contains multiple nodes/edges with the same key fields.

E.g.

Merge
  Company(id='Google', properties={'p1':'a1', 'p3':'a3'}),
  Company(id='Google', properties={'p2':'a2', 'p3':'a4'})
into
  Company(id='Google', properties={'p1':'a1', 'p2':'a2', 'p3':'a4'})

This is due to Spanner DML doesn't support updating the same row twice
in the same DML. We could also separate each node/edge into a separate
DML which can be very slow.

* style: formatting

* style: formatting

* Address various review feedbacks

1) Fix style of python notebook;
2) GraphStore:
   - improve a corner case by avoiding full set iteration;
   - add some null checking;
   - move utilities around.

* Format the notebook

* Fix linter error

* Fix type annotation

* Use batch table insertion API instead of transaction DML API

* Minor fixes & cleanups: colab, requirements, tests, schema corner cases

---------

Co-authored-by: Gaurav Purohit <purohitgaurav0612@gmail.com>
Co-authored-by: gauravpurohit <gauravpurohit@google.com>

Co-authored-by: release-please[bot] <55107282+release-please[bot]@users.noreply.github.com>