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