What does a proc_status of -6 mean?

Question

I'm trying to call a stored procedure in a database using the Sybase module for Python and I'm having this proc_status returned. I don't know what this proc_status means. Can anyone tell me? Code is attached below

#!/usr/bin/python_64
#coding=utf-8
import sybpydb

#Create a connection object
con = sybpydb.connect(
servername="********",
user="*******",
password="********" )

#Create a cursor object 
cur = con.cursor()

#start_date = '20170505'
#end_date = '20180505'
#dealer_code = '7802'
#dealer_rep_code = 'ZWF1'

try:
    cur.callproc('trans_history.sp', ['20170505','20180505','7802','ZWF1']) 
    continues = True
    while(continues == True):
        row = cur.fetchall()
        continues = cur.nextset()
except sybpydb.Error:
    print("Status=%d" % cur.proc_status)

#Close the connection
cur.close()
con.close()

Here is the output: Status= -6