old_contents: var warning = require('react/lib/warning');
  var invariant = require('react/lib/invariant');
  
  function checkPropTypes(componentName, propTypes, props) {
    for (var propName in propTypes) {
      if (propTypes.hasOwnProperty(propName)) {
        var error = propTypes[propName](props, propName, componentName);
  
        if (error instanceof Error)
          warning(false, error.message);
      }
    }
  }
  
  var Configuration = {
  
    statics: {
  
      validateProps: function (props) {
        checkPropTypes(this.displayName, this.propTypes, props);
      }
  
    },
  
    render: function () {
      invariant(
        false,
        '%s elements are for router configuration only and should not be rendered',
        this.constructor.displayName
      );
    }
  
  };
  
  module.exports = Configuration;
  
new_contents: var invariant = require('react/lib/invariant');
  
  var Configuration = {
  
    render: function () {
      invariant(
        false,
        '%s elements are for router configuration only and should not be rendered',
        this.constructor.displayName
      );
    }
  
  };
  
  module.exports = Configuration;
  
subject: Remove dead code