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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 _prepare_statement(sql_statement, parameters):
 """ Prepare the specified SQL statement, replacing the placeholders by the value of the given parameters @param sql_statement: the string expression of a SQL statement. @param parameters: a dictionary of parameters where the key represents the name of a parameter and the value represents the value of this parameter to replace in each placeholder of this parameter in the SQL statement. @return: a string representation of the SQL statement where the placehodlers have been replaced by the value of the corresponding variables, depending on the type of these variables. """

        placehoolders = RdbmsConnection._get_placeholders(sql_statement, parameters)

        for (variable_name, (variable_type, variable_value)) in placehoolders.iteritems():
            # Only expand parameters whose value corresponds to a list.
            if isinstance(variable_value, (list, set, tuple)):
                sql_statement = RdbmsConnection._replace_placeholder(sql_statement,
                        (variable_name, variable_type, variable_value))

                # Remove this parameter as it has been expended in the SQL expression.
                del parameters[variable_name]

        return sql_statement