default boolean containsFunction(String functionName, RankProfile rankProfile) {
        if (rankProfile.definedFunctions().containsKey(functionName))
            return true;
        for (var parentProfile : rankProfile.parents().values()) {
            if (containsFunction(functionName, parentProfile))
                return true;
        }
        return false;
    }
A function's declaration in the SD language.

@author Shahar Ariel
integration/intellij/src/main/java/ai/vespa/intellij/schema/psi/SdFunctionDefinitionInterface.java