old_contents: #!/usr/bin/env python
  
  from nodes import Node
  
  class BitXOR(Node):
      args = 2
      results = 1
      char = ".^"
      
      def prepare(self, stack):
          if len(stack) == 0:
              self.add_arg(stack)
          if isinstance(stack[0], Node.sequence):
                  self.args = 1
              
      @Node.test_func([4,5], [1])
      def func(self, a:int,b:int):
          """a^b"""
          return a^b
  
      @Node.test_func(["Test.", "Te"], [1])
      @Node.test_func(["Test.", "?"], [0])
      @Node.test_func(["Test.", "T"], [1])
      def startswith(self, string:str, suffix:str):
          """Does string start with suffix?"""
          return int(string.startswith(suffix))
      
      def xor_seq(self, seqs:Node.sequence):
          """Setwise xor of sequences"""
          if len(seqs)==0: return seqs
          rtn = []
          for seq in seqs:
              if isinstance(seq, Node.sequence):
                  for i in seq:
                      if i not in rtn:
                          rtn.append(i)
                      else:
                          rtn.remove(i)
              else:
                  if seq in rtn:
                      rtn.append(seq)
                  else:
                      rtn.remove(seq)
          return [rtn]
  
new_contents: #!/usr/bin/env python
  
  from nodes import Node
  
  class BitXOR(Node):
      args = 2
      results = 1
      char = ".^"
      
      def prepare(self, stack):
          if len(stack) == 0:
              self.add_arg(stack)
          if isinstance(stack[0], Node.sequence):
                  self.args = 1
              
      @Node.test_func([4,5], [1])
      def func(self, a:int,b:int):
          """a^b"""
          return a^b
  
      @Node.test_func(["Test.", "Te"], [1])
      @Node.test_func(["Test.", "?"], [0])
      @Node.test_func(["Test.", "T"], [1])
      def startswith(self, string:str, suffix:str):
          """Does string start with suffix?"""
          return int(string.startswith(suffix))
      
      def xor_seq(self, seqs:Node.sequence):
          """Setwise xor of sequences"""
          if len(seqs)==0: return seqs
          rtn = []
          for seq in seqs:
              if isinstance(seq, Node.sequence):
                  for i in seq:
                      if i not in rtn:
                          rtn.append(i)
                      else:
                          rtn.remove(i)
              else:
                  if seq not in rtn:
                      rtn.append(seq)
                  else:
                      rtn.remove(seq)
          return [rtn]
  
subject: Fix Bug