title: What is a subtraction function that is similar to sum() for subtracting items in list?
body: <p>I am trying to create a calculator, but I am having trouble writing a function that will subtract numbers from a list.<br>
  For example:</p>
  
  <pre><code>class Calculator(object):
      def __init__(self, args):
          self.args = args
  
      def subtract_numbers(self, *args):
          return ***here is where I need the subtraction function to be****
  </code></pre>
  
  <p>For addition, I can simply use return <code>sum(args)</code> to calculate the total but I am unsure of what I can do for subtractions.</p>