foo -> UMethod (name = foo)
Boolean -> USimpleNameReferenceExpression (identifier = Boolean)
    x -> [!] UnknownKotlinExpression (PROPERTY)
    y -> [!] UnknownKotlinExpression (PROPERTY)
    x -> USimpleNameReferenceExpression (identifier = x)
    in -> USimpleNameReferenceExpression (identifier = in)
    .. -> USimpleNameReferenceExpression (identifier = ..)
    && -> USimpleNameReferenceExpression (identifier = &&)
    y -> USimpleNameReferenceExpression (identifier = y)
    !in -> USimpleNameReferenceExpression (identifier = !in)
    .. -> USimpleNameReferenceExpression (identifier = ..)
