protected function buildNode(array $ast, string $propertyName): ?NodeInterface
    {
        return isset($ast[$propertyName]) ? $this->build($ast[$propertyName]) : null;
    }
protected function buildNode(array $ast, string $propertyName): ?NodeInterface
    {
        return isset($ast[$propertyName]) ? $this->build($ast[$propertyName]) : null;
    }
protected function buildNode ( array $ ast , string $ propertyName ) : ? NodeInterface { return isset ( $ ast [ $ propertyName ] ) ? $ this -> build ( $ ast [ $ propertyName ] ) : null ; }
Builds a single item from the given AST.

@param array  $ast
@param string $propertyName
@return NodeInterface|null
@throws LanguageException
Builds a single item from the given AST .