from io import StringIO

dangerous_sink = print

class Source:
    def __init__(self, stream: StringIO|None = None):
        self.stream = stream if stream is not None else StringIO()

    def read(self):
        return self.stream.getvalue()

    def writecontent(self, content):
        self.stream.write(content)

class Processor:
    def process(self, s: Source):
        s.stream.seek(0)
        source_code = s.stream.getvalue()
        dangerous_sink(test_global + "" + source_code)

test_global = "test_data"   
tainted_global = "tainted_data"     
        
if __name__ == "__main__":

    s = Source()
    c = Processor()
    s.writecontent(tainted_global)
    c.process(s)

 predicate isAdditionalFlowStep(DataFlow::Node pred, DataFlow::Node succ) {
    exists(DataFlow::MethodCallNode m|
      m.getMethodName() = "write" and
      m.getObject() = succ and
      pred = m.getArg(0) 
    )
    or
    exists(DataFlow::MethodCallNode m |
      m.getMethodName() = "write" and
      m.getObject() = pred
      and pred.asExpr().(Attribute).getObject() = succ.asExpr()
    )
    or
    exists(DataFlow::MethodCallNode m|
      m.getMethodName() in ["getvalue", "read"] and
      succ = m
      and pred = m.getObject()
    )

 }