import psycopg2
try:
    conn = psycopg2.connect("dbname='mb_sed_class' user='postgres' host='localhost' password='Daniel'")
except:
    print "I am unable to connect to the database"

print ("I connected to the database")
cur = conn.cursor()
cur.execute("select relname from pg_class where relkind='r' and relname !~ '^(pg_|sql_)';")
print cur.fetchall()

psql -d mb_sed_clsss -U postgres

FATAL: pssword Authentication failed for user "postgres"