con = psycopg2.connect(dbname=dbname, host=host, port=port, user=user, password=password)
cur = con.cursor()

try3 = "TRUNCATE TABLE (%s);"
values = ("schema_one.tbl_six",)
cur.execute(try3,values)

try4 = "TRUNCATE TABLE %s;"
values = ("schema_four.tbl_four",)
cur.execute(try4,values)

$ ./test_qry.py
Traceback (most recent call last):
  File "./test_qry.py", line 23, in <module>
    cur.execute(try3,values)
psycopg2.ProgrammingError: syntax error at or near "("
LINE 1: TRUNCATE TABLE ('schema_one.tbl_six');

$ ./test_qry.py
Traceback (most recent call last):
  File "./test_qry.py", line 28, in <module>
    cur.execute(try4,values)
psycopg2.ProgrammingError: syntax error at or near "'schema_four.tbl_four'"
LINE 1: TRUNCATE TABLE 'schema_four.tbl_four';