How to capture terminal output to text file from my python script

I want to capture terminal message and save it to a text file while my python script is running.. I want to capture error messages as well.

-Don't want to execute this using batch file.
-help me where should i put those command on my script

import base64

import sendgrid


import os

import pandas as pd

import time

from datetime import date, timedelta



from sendgrid.helpers.mail import Email, Content, Mail, Attachment

    # Python 3
    import urllib.request as urllib

except ImportError:

    # Python 2
    import urllib2 as urllib



list = pd.read_csv('emaildb.csv')

email = list['Email']

merchant = list['Merchant']

today = date.today()

yest = today - timedelta(1)


yest1 = yest.strftime('%Y%m%d')

yest2 = yest.strftime('%Y-%m-%d')

now1 = time.strftime("%B %d %Y  %H:%M:%S") 

sg = sendgrid.SendGridAPIClient(apikey='sample API')




i = 0

while i < len(list):

    file_name1 = "REPORT_"+yest1+"_"+str(merchant[i])+".pdf"

    file_name2 = "REPORT_"+yest1+"_"+str(merchant[i])+".xls"

    S1="REPORT "+str(merchant[i])+" "+str(yest1)


    B1 = "Test"

    with open(file_name1,'rb') as f:
        data1 = f.read()
    encoded1 = base64.b64encode(data1).decode()



    with open(file_name2,'rb') as f:

        data2 = f.read()
    encoded2 = base64.b64encode(data2).decode()

    mail = {
        "attachments": [
        {
          "content": encoded1, 

          "filename": file_name1,
        },

        {
          "content": encoded2,
          "filename": file_name2,
        }
      ],      
      "personalizations": [
        {

          "to": [{
              "email": email[i]

          }],
          "subject": S1
        }
      ],
      "from": {
        "email": "test.com"
      },
      "content": [
        {
          "type": "text/html",

          "value": B1
        }
      ]
    }

    response = sg.client.mail.send.post(request_body=mail)
    print("["+now1+"] "+email[i]+" "+file_name1)
    if response.status_code == 202:
        print('Success')
    else: print('Failed')

    print("\n")
    i = i + 1