title: Python Class gives "None in the ouptut"
body: <p>I have the following code:</p>
  
  <pre><code>class StudentData:
      "Contains information of all students"
      studentNumber = 0;
      def __init__(self,name,age,marks):
          self.name = name;
          self.age = age;
          self.marks = marks;
          StudentData.studentNumber += 1;
      def displayStudentNumber(self):
          print 'Total Number of students = ',StudentData.studentNumber;
      def displayinfo(self):
          print 'Name of the Student: ',self.name;
          print 'Age of the Student: ', self.age;
          print 'Marks of the Student: ', self.marks;
  
  student1 = StudentData('Ayesha',12,90)
  student2 = StudentData('Sarah',13,89)
  print "*Student number in case of student 1*\n",student1.displayStudentNumber();
  print "Information of the Student",student1.displayinfo();
  print "*Student number in case of student 2*\n",student2.displayStudentNumber();
  print "Information of the Student",student2.displayinfo();
  </code></pre>
  
  <p>And the output is:</p>
  
  <pre>
  *Student number in case of student 1*
  
  Total Number of students =  2
  
  None
  
  Information of the Student Name of the Student:  Ayesha
  
  Age of the Student:  12
  
  Marks of the Student:  90
  
  None
  
  *Student number in case of student 2*
  
  Total Number of students =  2
  
  None
  
  Information of the Student Name of the Student:  Sarah
  
  Age of the Student:  13
  
  Marks of the Student:  89
  
  None
  </pre>
  
  <p>I can't understand why do I get these "None" in my output. Can anyone explain it?</p>