Phan\CodeBase::hasInternalFunctionWithFQSEN PHP Method

    private function hasInternalFunctionWithFQSEN(FullyQualifiedFunctionName $fqsen) : bool
    {
        // Only root namespaced functions will be found in
        // the internal function map.
        if ($fqsen->getNamespace() != '\\') {
            return false;
        }
        // For elements in the root namespace, check to see if
        // there's a static method signature for something that
        // hasn't been loaded into memory yet and create a
        // method out of it as its requested
        $function_signature_map = UnionType::internalFunctionSignatureMap();
        if (!empty($function_signature_map[$fqsen->getNameWithAlternateId()])) {
            $signature = $function_signature_map[$fqsen->getNameWithAlternateId()];
            // Add each method returned for the signature
            foreach (FunctionFactory::functionListFromSignature($this, $fqsen, $signature) as $i => $function) {
                $this->addFunction($function);
            }
            return true;
        }
        return false;
    }