diff --git a/MainPresenter.py b/MainPresenter.py
index 43fef43..23d934e 100644
--- a/MainPresenter.py
+++ b/MainPresenter.py
@@ -34,13 +34,13 @@ class MainPresenter:
             thread.start()
 
     def on_thread_exit(self, is_last):
-        if is_last == True:
+        if is_last:
             self.isScanEnabled = False
             self.ui.startButton.setText("Start")
             return
         count = 0
         for thr in self.threads:
-            if thr.is_running == True:
+            if thr.is_running:
                 count = count + 1
         self.setCurrentThreadsLabel(count)
 
@@ -52,7 +52,7 @@ class MainPresenter:
             count = 0
             is_last_thread = False
             for i in self.threads:
-                if i.is_running != True:
+                if not i.is_running:
                     count += 1
             if count == len(self.threads):
                 is_last_thread = True
@@ -90,7 +90,7 @@ class ScanThread(QThread):
                 count = 0
                 is_last_thread = False
                 for i in self.presenter.threads:
-                    if i.isRunning() != True:
+                    if not i.isRunning():
                         count += 1
                 if count == len(self.presenter.threads):
                     is_last_thread = True
diff --git a/Parser.py b/Parser.py
index 3da1ff2..c73ee8c 100644
--- a/Parser.py
+++ b/Parser.py
@@ -2,53 +2,75 @@ import ipaddress
 
 
 def getPortsFromString(ports):
-    # Converts ports from form 20-40,100-900,40000-70000
-    # It will automatically prune off non-existent ports (<1 >65535)
-    if ports is None:
-        return [21, 22, 23, 25, 80, 443, 110, 111, 135, 139, 445, 8080, 8443, 53, 143, 989, 990, 3306, 1080, 5554, 6667, 2222, 4444, 666, 6666, 1337, 2020, 31337] # Change to default ports from constant
-    else:
-        if "-" not in ports:
-            tports = ports.split(",")
-            print(tports)
-        else:
-            ports = ports.split(",")
-            tports = []
-            for port in ports:
-                if "-" not in port:
-                    tports.append(int(port))
+    """
+    Parses ports from string, returns them as integers in the list.
+    Handles non-existent ports and non-port values.
+    """
+    if ports:
+        # Using set to avoid repetitions
+        parsed = set()
+        ports = ports.split(",")
+        for port in ports:
+            try:
+                # Input is in range form ("100-200"):
+                if '-' in port:
+                    start, end = map(int, port.split('-'))
+                    parsed.update(
+                        [p for p in range(start, end + 1) if 65355 >= p > 0])
+                # Input is a single port ("80"):
                 else:
-                    # I made this one line because I wanted to
-                    tports.extend(
-                        list(range(int(port.split("-")[0]), int(port.split("-")[1]) + 1)))
-    ports = [int(n) for n in tports if int(n) > 0 and int(n) < 65536]
-    return ports
+                    parsed.add(int(port))
+            except ValueError as e:
+                # If we get any not integer just ignore it
+                pass
+        return sorted(list(parsed))
+    else:
+        # Change to default ports from constant
+        return [21, 22, 23, 25, 80, 443, 110, 111, 135, 139, 445, 8080, 8443, 53, 143, 989, 990, 3306, 1080, 5554, 6667, 2222, 4444, 666, 6666, 1337, 2020, 31337]
 
 
 def getCIDRFromRanges(ips):
+    """
+    Parses ip input string, returns the generator over them.
+
+    Supports next inputs:
+        1) 1.2.3.4
+        2) 192.168.0.0/24
+        3) 1.2.3.4 - 5.6.7.8
+    Any non-ip value will be ignored.
+    """
+
+    # A set to contain non repeating ip objects from ipaddress
     ip_objects = set()
     inputs = [ip.strip() for ip in ips.split(',')]
 
     for input_ in inputs:
         try:
+            # Input is in range form ("1.2.3.4 - 5.6.7.8"):
             if '-' in input_:
                 input_ips = input_.split('-')
                 ranges = {ipaddr for ipaddr in ipaddress.summarize_address_range(
                     ipaddress.IPv4Address(input_ips[0]),
                     ipaddress.IPv4Address(input_ips[1]))
-                               }
+                }
                 ip_objects.update(ranges)
+            # Input is in CIDR form ("192.168.0.0/24"):
             elif '/' in input_:
                 network = ipaddress.ip_network(input_)
                 ip_objects.add(network)
+            # Input is a single ip ("1.1.1.1"):
             else:
                 ip = ipaddress.ip_address(input_)
                 ip_objects.add(ip)
         except ValueError as e:
-            print(e)
+            # If we get any non-ip value just ignore it
+            pass
 
     for ip_obj in ip_objects:
-        if not isinstance(ip_obj, ipaddress.IPv4Address):
-            for ip in ip_obj.hosts():
-                yield ip
-        else:
+        # The object is just one ip, simply yield it:
+        if isinstance(ip_obj, ipaddress.IPv4Address):
             yield ip_obj
+        # The object is a network, yield every host in it:
+        else:
+            for host in ip_obj.hosts():
+                yield host
diff --git a/main.py b/main.py
index b16c9af..455abd3 100644
--- a/main.py
+++ b/main.py
@@ -19,15 +19,17 @@ class MyWin(QtWidgets.QMainWindow):
         self.isScanActive = False
 
     def startButtonClicked(self):
-        if self.presenter.isScanEnabled == False:
-            self.presenter.isScanEnabled = True
-            self.ui.startButton.setText("Stop")
-            self.presenter.startScan(self.ui.ipLine.text(), self.ui.portsLine.text(), self.ui.threadsLine.text(),
-                                     self.ui.timeoutLine.text())
-        else:
+        if self.presenter.isScanEnabled:
             self.presenter.isScanEnabled = False
             self.ui.startButton.setText("Start")
             self.presenter.stopScan()
+        else:
+            self.presenter.isScanEnabled = True
+            self.ui.startButton.setText("Stop")
+            self.presenter.startScan(self.ui.ipLine.text(),
+                                     self.ui.portsLine.text(),
+                                     self.ui.threadsLine.text(),
+                                     self.ui.timeoutLine.text())
 
 
 if __name__ == "__main__":