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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def export(self, exclude=[]):
 """ returns a dictionary representation of the document """

        fields = ( (key, self.get_field(key)) for key in self.schema
            if not key.startswith("_") and key not in exclude )
        
        doc = {name: field.export() for name, field in fields}
        return doc