title: Python IndentationError: “expected an indented block” on Xcode
body: <p>I've been getting this error on xcode and vi. Python says the line class LeastModel has an IndentationError: expected an indented block.
  I checked my preferences on Xcode to use 4 spaces for a tab and everywhere I've been using tab. Please help me!</p>
  
  <pre><code>def make_model(data,model):
  
  class LeastModel():
      """
      linear system solved using linear least squares
      This class serves as an example that fulfills the model interface needed by the ransa function.
      """
      def __init__(self,input_columns,output_columns):
          self.input_columns = input_columns
          self.output_columns = output_columns
          #self.debug = debug
  </code></pre>