Building Firedrake on Archer2

Please follow the following to build and test Firedrake on Archer2.

Pick your work directory (e.g., /work/your_account/shared), set WORK environment variable, and cd to $WORK:
```
export WORK=/your/work/dir
mkdir -p $WORK
cd $WORK
```
Pick Firedrake install directory (e.g., $WORK/firedrake) and set $FIREDRAKE_DIR environment variable:
```
export FIREDRAKE_DIR=/your/firedrake/install/dir
```

Clone this repository in $FIREDRAKE_DIR:

git clone https://github.com/firedrakeproject/firedrake-archer2.git $FIREDRAKE_DIR

Build Firedrake by running:
```
bash $FIREDRAKE_DIR/firedrake_install_archer2.sh
```
This will take about 30 minutes.
To test installation, move $FIREDRAKE_DIR/job.slurm and $FIREDRAKE_DIR/example.py to the current directory. In job.slurm, change the account name to your own account name and the FIREDRAKE_DIR environment variable to $FIREDRAKE_DIR and then submit the job:
```
mv $FIREDRAKE_DIR/job.slurm job.slurm
mv $FIREDRAKE_DIR/example.py example.py
# Change account name and FIREDRAKE_DIR environment variable in job.slurm.
sbatch job.slurm
```

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