how to install PostgreSQL functions in python?

psycopg2 is a solid wrapper for PostgreSQL. From the docs:

DSN = 'dbname=test'

## don't modify anything below this line (except for experimenting)

class SimpleQuoter(object):
    def sqlquote(x=None):
        return "'bar'"

import sys
import psycopg2

if len(sys.argv) > 1:
    DSN = sys.argv[1]

print("Opening connection using dsn:", DSN)
conn = psycopg2.connect(DSN)
print("Encoding for this connection is", conn.encoding)

curs = conn.cursor()
curs.execute("SELECT 1 AS foo")
print(curs.fetchone())
curs.execute("SELECT 1 AS foo")
print(curs.fetchmany())
curs.execute("SELECT 1 AS foo")
print(curs.fetchall())

conn.rollback()

sys.exit(0)

curs.execute("SELECT 1 AS foo", async=1)

curs.execute("SELECT %(foo)s AS foo", {'foo':'bar'})
curs.execute("SELECT %(foo)s AS foo", {'foo':None})
curs.execute("SELECT %(foo)f AS foo", {'foo':42})
curs.execute("SELECT %(foo)s AS foo", {'foo':SimpleQuoter()})