diff --git a/README.md b/README.md
index b6f72c6..d6e1b73 100644
--- a/README.md
+++ b/README.md
@@ -16,10 +16,10 @@ Sitemap-generator uses [gevent](http://www.gevent.org/) to implement multiproces
     import pysitemap
 
 
-    if __name__=='__main__':
-        url = 'http://www.example.com/' # url from to crawl
-        logfile = 'errlog.log' # path to logfile
-        oformat = 'xml' # output format
+    if __name__ == '__main__':
+        url = 'http://www.example.com/'  # url from to crawl
+        logfile = 'errlog.log'  # path to logfile
+        oformat = 'xml'  # output format
         crawl = pysitemap.Crawler(url=url, logfile=logfile, oformat=oformat)
         crawl.crawl()
 
@@ -30,9 +30,9 @@ Sitemap-generator uses [gevent](http://www.gevent.org/) to implement multiproces
     import pysitemap
 
 
-    if __name__=='__main__':
-        url = 'http://www.example.com/' # url from to crawl
-        logfile = 'errlog.log' # path to logfile
-        oformat = 'xml' # output format
+    if __name__ == '__main__':
+        url = 'http://www.example.com/'  # url from to crawl
+        logfile = 'errlog.log'  # path to logfile
+        oformat = 'xml'  # output format
         crawl = pysitemap.Crawler(url=url, logfile=logfile, oformat=oformat)
-        crawl.crawl(pool_size=10) # 10 parsing processes
+        crawl.crawl(pool_size=10)  # 10 parsing processes
diff --git a/pysitemap/crawler.py b/pysitemap/crawler.py
index c48a7bd..11b11a4 100644
--- a/pysitemap/crawler.py
+++ b/pysitemap/crawler.py
@@ -1,16 +1,12 @@
-import urllib
-from bs4 import BeautifulSoup
 import urlparse
 import mechanize
-import pickle
 import re
-try:                    
+try:
     import sys
     if 'threading' in sys.modules:
         del sys.modules['threading']
         print('threading module loaded before patching!')
         print('threading module deleted from sys.modules!\n')
-    import gevent
     from gevent import monkey, pool
     monkey.patch_all()
     gevent_installed = True
@@ -36,7 +32,7 @@ class Crawler:
         self.exts = exts
 
     def allow_regex(self, regex=None):
-        if not regex is None:
+        if regex is not None:
             self.allowed_regex = regex
         else:
             allowed_regex = ''
@@ -71,7 +67,7 @@ class Crawler:
             else:
                 print('{} pages parsed :: {} parsing processes  :: {} pages in the queue'.format(len(self.visited), len(self.pool), len(self.urls)))
 
-        # Set the startingpoint for the spider and initialize 
+        # Set the startingpoint for the spider and initialize
         # the a mechanize browser object
 
         if not self.urls:
@@ -84,10 +80,10 @@ class Crawler:
                 if response.code >= 400:
                     self.errlog("Error {} at url {}".format(response.code, url))
                     return
-                           
+
                 for link in br.links():
-                    newurl =  urlparse.urljoin(link.base_url, link.url)
-                    #print newurl
+                    newurl = urlparse.urljoin(link.base_url, link.url)
+                    # print(newurl)
                     if self.is_valid(newurl):
                         self.visited.update([newurl])
                         self.urls.update([newurl])
@@ -97,15 +93,12 @@ class Crawler:
             br.close()
             del(br)
 
-
-
     def is_valid(self, url):
-        valid = False
         if '#' in url:
             url = url[:url.find('#')]
         if url in self.visited:
             return False
-        if not self.url in url:
+        if self.url not in url:
             return False
         if re.search(self.regex, url):
             return False
@@ -132,4 +125,4 @@ class Crawler:
         while self.visited:
             of.write(url_str.format(self.visited.pop()))
 
-        of.close()
\ No newline at end of file
+        of.close()
diff --git a/run.py b/run.py
index 85cbe14..82d8947 100644
--- a/run.py
+++ b/run.py
@@ -7,10 +7,10 @@ To install gevent:
     $ pip install gevent
 """
 
-if __name__=='__main__':
-    url = 'http://www.example.com/' # url from to crawl
-    logfile = 'errlog.log' # path to logfile
-    oformat = 'xml' # output format
-    outputfile = 'sitemap.xml' # path to output file
+if __name__ == '__main__':
+    url = 'http://www.example.com/'  # url from to crawl
+    logfile = 'errlog.log'  # path to logfile
+    oformat = 'xml'  # output format
+    outputfile = 'sitemap.xml'  # path to output file
     crawl = pysitemap.Crawler(url=url, logfile=logfile, oformat=oformat, outputfile=outputfile)
     crawl.crawl(pool_size=20)