[https://github.com/starkware-libs/cairo-lang/blob/54d7e92a703b3b5a1e07e9389608178129946efc/src/starkware/starknet/compiler/external_wrapper.py#L65](https://github.com/starkware-libs/cairo-lang/blob/54d7e92a703b3b5a1e07e9389608178129946efc/src/starkware/starknet/compiler/external_wrapper.py#L65)

this should be what you're looking for

Do any of you know where I can find the list of the decorators available in Cairo, please?

Newton

List of Cairo Decorators

Hello. Does starknet have name service? what is the difference between starknet id and starknet name service? Are they same projects?

_This question was originally posted on [StarkNet Discord](https://www.newton.so/view?tags=discord)_

Does starknet have name service? 

Hello! This is day 12 of the 17 days of the Cairo Challenge. And I have no idea how to solve the [playground](https://www.cairo-lang.org/playground/) exercise “Structs.  Perhaps you can help me?

```
// In this challenge you're going to implement a stack using a linked list.
//
// Add the missing code so that main() runs successfully.

from starkware.cairo.common.registers import get_fp_and_pc

struct Node {
    // A pointer to the next node in the stack.
    next: Node*,

    // The value of the node.
    value: felt,

    // The number of elements in the stack.
    size: felt,
}

// Returns an empty stack.
func empty_stack() -> (stack: Node*) {
    alloc_locals;
    local new_node: Node;
    assert new_node.next = cast(0, Node*);
    assert new_node.value = 0;
    assert new_node.size = 0;

    // The usage of get_fp_and_pc() here is necessary in order
    // to access the address of a local variable (&new_node).
    // You can read more about get_fp_and_pc() [here](https://cairo-lang.org/docs/how_cairo_works/functions.html#retrieving-registers).
    let (local __fp__, _) = get_fp_and_pc();
    return (stack=&new_node);
}

// Adds a node to the top of the stack.
// Returns the updated stack (since Cairo is immutable, you can still use the
// old copy of the stack).
func push(stack: Node*, value: felt) -> (stack: Node*) {
    alloc_locals;
    local new_node: Node;
    // Fix and uncomment below.
    // assert new_node.next = ...
    // assert new_node.value = ...
    // assert new_node.size = ...

    let (__fp__, _) = get_fp_and_pc();
    return (stack=&new_node);
}

// Removes the top element of the stack.
// Returns the updated stack and the element that was removed.
func pop(stack: Node*) -> (stack: Node*, value: felt) {
    return (stack=stack.next, value=stack.value);
}

// Returns the value of the n-th element from the top of the stack.
func stack_at(stack: Node*, n: felt) -> (value: felt) {
    if (n == 0) {
        // Add your code here.
    }

    // Add your code here.
}

func main() -> () {
    alloc_locals;
    // Start with an empty stack.
    let (stack) = empty_stack();
    // Push 1, 10, 100.
    let (stack) = push(stack, 1);
    let (stack) = push(stack, 10);
    let (local stack) = push(stack, 100);

    // Check the size of the stack.
    assert stack.size = 3;

    // Query the stack at indices 0, 1 and 2.
    let (value) = stack_at(stack, 0);
    assert value = 100;
    let (value) = stack_at(stack, 1);
    assert value = 10;
    let (value) = stack_at(stack, 2);
    assert value = 1;

    // Pop the top 2 values (100 and 10) and push 1000.
    let (stack, value) = pop(stack);
    assert value = 100;
    let (stack, value) = pop(stack);
    assert value = 10;
    let (local stack) = push(stack, 1000);

    // Query the stack at indices 0 and 1.
    let (value) = stack_at(stack, 0);
    assert value = 1000;
    let (value) = stack_at(stack, 1);
    assert value = 1;

    return ();
}
```

---

> Answers to this question are a part of the ✨ 17 days of Cairo Lang with Playground & Newton. ✨
> 

*Vote for your favorite answer - the best answer will win a $10 award. A new day – a new reward! During the next 17 days, our goal is to attract more developers to the Cairo language and to systematize the knowledge of Cairo lang. [Read rules](https://www.notion.so/17-days-of-Cairo-Lang-with-Newton-550dfcda6a2d449ca468be293c776578)*

How to create Structs in Cairo Lang for StarkNet?

hi, i used the starkgate bridge from stark to eth one hour ago. Withdrawal has not occurred yet. How many hours does the process take? My tx hash is: <address>cfa0c02d013658804505506

_This question was originally posted on [StarkNet Discord](https://www.newton.so/view?tags=discord)_

How many time does it take for stark to eth starkgate bridge process?

Hello there,

Do you know why `pedersen_hash` needs to split felts in low 248 and high 4 bits? 

---

This question is participating in [Newton Bounties | Incentivized Test Program](https://www.notion.so/Newton-Bounties-Incentivized-Test-Program-94322ad48e7d40a3adcf36f6b26174cd) Every verified valid question gets $10 USDC (mainnet)

Why does Starkware pedersen Hash Function split numbers in high and low bits

How to verify Empiric’s Data Entries Using Events?

Hello! This is day 9 of the 17 days of the Cairo Challenge. And I have no idea how to solve the [playground](https://www.cairo-lang.org/playground/) exercise “Field Elements 2”.  Perhaps you can help me?

```
// As you saw in the previous challenge, the operator '/' does not denote
// truncated (i.e., rounding down) integer division as in other programming
// languages. Instead, one can use library functions such as
// unsigned_div_rem().
//
// Note that unsigned_div_rem() does not work for negative numbers.

%builtins output range_check

// Import unsigned_div_rem() from the math module.
from starkware.cairo.common.math import unsigned_div_rem
from starkware.cairo.common.serialize import serialize_word

func main{output_ptr: felt*, range_check_ptr}() {
    let (q, r) = unsigned_div_rem(value=12, div=3);
    // Output the quotient (12 // 3).
    serialize_word(q);
    // Output the remainder (12 % 3).
    serialize_word(r);

    // Add code that outputs the quotient and remainder of 13 / 3 in addition to 12 / 3 here.

    return ();
}
```

---

> Answers to this question are a part of the ✨ 17 days of Cairo Lang with Playground & Newton. ✨
> 

*Vote for your favorite answer - the best answer will win a $10 award. A new day – a new reward! During the next 17 days, our goal is to attract more developers to the Cairo language and to systematize the knowledge of Cairo lang. [Read rules](https://www.notion.so/17-days-of-Cairo-Lang-with-Newton-550dfcda6a2d449ca468be293c776578)*

How to divide felt in Cairo Lang using unsigned_div_rem?

I used the Nethermind Warp Traspiler to translate the Solidity to Cairo successfully, but there was a problem with the test. I don't think there is this `warplib` package, `node_module` there is, but there is no python package. How do I generate python packages?


```python
from warplib.memory import wm_new
from warplib.maths.utils import felt_to_uint256
```

### How to represent / my environment
I used python virtual environment to develop cairo, and then I used this tool to convert solidity to cairo. After compiling, I reported an error and saw that `the warp-related package was not found`.

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List of Cairo Decorators

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