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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 add_statements(self, stmts):
 """Add INDRA Statements to the assembler's list of statements. Parameters stmts : list[indra.statements.Statement] A list of :py:class:`indra.statements.Statement` to be added to the statement list of the assembler. """

        for stmt in stmts:
            if not self.statement_exists(stmt):
                self.statements.append(stmt)