diff --git a/pyinvoice/models.py b/pyinvoice/models.py
index 5c9de76..4cf52df 100644
--- a/pyinvoice/models.py
+++ b/pyinvoice/models.py
@@ -2,6 +2,9 @@ from __future__ import unicode_literals
 
 
 class PDFInfo(object):
+    """
+    PDF Properties
+    """
     def __init__(self, title=None, author=None, subject=None):
         self.title = title
         self.author = author
@@ -77,6 +80,13 @@ class Transaction(object):
     Transaction information
     """
     def __init__(self, gateway, transaction_id, transaction_datetime, amount):
+        """
+        :param gateway: Payment gateway like Paypal, Stripe etc.
+        :param transaction_id:
+        :param transaction_datetime:
+        :param amount: $$
+        :return:
+        """
         self.gateway = gateway
         self.transaction_id = transaction_id
         self.transaction_datetime = transaction_datetime
diff --git a/pyinvoice/templates.py b/pyinvoice/templates.py
index 98cbd9d..d33b972 100644
--- a/pyinvoice/templates.py
+++ b/pyinvoice/templates.py
@@ -5,6 +5,7 @@ from reportlab.lib.pagesizes import letter
 from reportlab.lib.styles import getSampleStyleSheet, ParagraphStyle
 from reportlab.lib.units import inch
 from reportlab.platypus import SimpleDocTemplate, Paragraph
+
 from pyinvoice.components import SimpleTable, TableWithHeader, PaidStamp
 from pyinvoice.models import PDFInfo, Item, Transaction, InvoiceInfo, ServiceProviderInfo, ClientInfo
 
diff --git a/test.py b/test.py
index 34c4ad2..b4f0964 100644
--- a/test.py
+++ b/test.py
@@ -1,8 +1,10 @@
 from datetime import datetime
 from decimal import Decimal
+
 from pyinvoice.models import InvoiceInfo, ServiceProviderInfo, ClientInfo, Item, Transaction
 from pyinvoice.templates import SimpleInvoice
 
+
 doc = SimpleInvoice('test.pdf')
 
 doc.is_paid = True