title: How to determine whether a year is a leap year?
body: <p>I am trying to make a simple calculator to determine whether or not a certain year is a leap year. </p>
  
  <p>By definition, a leap year is divisible by four, but not by one hundred, unless it is divisible by four hundred.</p>
  
  <p>Here is my code:</p>
  
  <pre><code>def leapyr(n):
      if n%4==0 and n%100!=0:
          if n%400==0:
              print(n, "is a leap year.")
      elif n%4!=0:
          print(n, "is not a leap year.")
  print(leapyr(1900))
  </code></pre>
  
  <p>When I try this inside the Python IDLE, the module returns <code>None</code>. I am pretty sure that I should get <code>1900 is a leap year</code>.</p>