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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 lookup(self, section, name):
 """Lookup config value."""

        value = os.environ.get('AMAAS_{}'.format(name.upper()))
        if value:
            return value

        try:
            value = self.file_config.get(section, name)
        except ConfigParserError:
            pass
        else:
            if value:
                return value

        raise MissingConfigurationError(section, name)