Como faço para criar um usuário postgresql com tecido

# In fabfile.py
def create_database():
    """Creates role and database"""
    db_user = get_user()  # define these
    db_pass = get_pass()
    db_name = get_db_name()
    sudo('psql -c "CREATE USER %s WITH NOCREATEDB NOCREATEUSER " \
         "ENCRYPTED PASSWORD E\'%s\'"' % (db_user, db_pass), user='postgres')
    sudo('psql -c "CREATE DATABASE %s WITH OWNER %s"' % (
         db_name, db_user), user='postgres')