comefrom: <garvit244>144_1.py
code: def preorderTraversal( root):
      if not root:
          return []
      
      stack, result = [root], []
      while stack:
          element = stack.pop()
          result.append(element.val)
      
          if element.right:
              stack.append(element.right)
          if element.left:
              stack.append(element.left)
      
      return result
masked: def sample_funcname ( var_0 ) :
      if not var_0 :
          return [ ]
      var_1 , var_2 = [ var_0 ] , [ ]
      while var_1 :
          var_4 = var_1.pop ( )
          var_2.append ( var_4.val )
          if var_4.right :
              var_1.append ( var_4.right )
          if var_4.left :
              var_1.append ( var_4.left )
      return var_2
  