feat: Add `__repr__` to NftId, TokenTransfer, and TokenNftTransfer

[Om7035]

Problem

Currently, the following classes in the src/hiero_sdk_python/tokens/ directory have str methods but are missing __repr__ methods:

1. NftId (src/hiero_sdk_python/tokens/nft_id.py)
2. TokenTransfer (src/hiero_sdk_python/tokens/token_transfer.py)
3. TokenNftTransfer (src/hiero_sdk_python/tokens/token_nft_transfer.py)

According to Python best practices (PEP 257), classes should implement both str and __repr__ methods:

• str() - Returns a human-readable string representation
• __repr__() - Returns an unambiguous string representation that ideally could be used to recreate the object

Current State:

• All three classes have str implemented ✅
• None of them have __repr__ implemented ❌

Inconsistency:
Other similar classes in the same module already have __repr__ methods:

• HbarTransfer has both str and __repr__
• HbarAllowance has both str and __repr__
• TokenAllowance has both str and __repr__
• TokenNftAllowance has both str and __repr__

Proposed Solution

Add __repr__ methods to all three classes following the existing pattern used in other token classes.

Implementation Details

1. For NftId class (src/hiero_sdk_python/tokens/nft_id.py)

Add a __repr__ method after the existing str method (after line 135):

def __repr__(self) -> str:
    """
    Returns an unambiguous string representation of the NftId.
    
    Returns:
        str: A string that could be used to recreate the NftId object.
    """
    return f"NftId(token_id={self.token_id!r}, serial_number={self.serial_number!r})"

2. For TokenTransfer class (src/hiero_sdk_python/tokens/token_transfer.py)

Add a __repr__ method after the existing str method (after line 70):

def __repr__(self) -> str:
    """
    Returns an unambiguous string representation of the TokenTransfer.
    
    Returns:
        str: A string that could be used to recreate the TokenTransfer object.
    """
    return (
        f"TokenTransfer("
        f"token_id={self.token_id!r}, "
        f"account_id={self.account_id!r}, "
        f"amount={self.amount!r}, "
        f"expected_decimals={self.expected_decimals!r}, "
        f"is_approved={self.is_approved!r})"
    )

3. For TokenNftTransfer class (src/hiero_sdk_python/tokens/token_nft_transfer.py)

Add a __repr__ method after the existing str method (after line 95):

def __repr__(self) -> str:
    """
    Returns an unambiguous string representation of the TokenNftTransfer.
    
    Returns:
        str: A string that could be used to recreate the TokenNftTransfer object.
    """
    return (
        f"TokenNftTransfer("
        f"token_id={self.token_id!r}, "
        f"sender_id={self.sender_id!r}, "
        f"receiver_id={self.receiver_id!r}, "
        f"serial_number={self.serial_number!r}, "
        f"is_approved={self.is_approved!r})"
    )

Benefits

1. Consistency - Aligns with other token classes that already have __repr__
2. Better Debugging - Provides clearer object representation in debuggers and logs
3. Python Best Practices - Follows PEP 257 guidelines
4. Developer Experience - Makes it easier to inspect objects during development

Acceptance Criteria

• Add __repr__ method to NftId class
• Add __repr__ method to TokenTransfer class
• Add __repr__ method to TokenNftTransfer class
• All __repr__ methods include Google-style docstrings
• Update CHANGELOG.md with the changes
• All commits are GPG signed (-S) and DCO signed (-s)
• Code passes pylint with 10/10 rating
• All tests pass

[Om7035]

I'd like to work on this" to get assigned

[exploreriii]

Thanks @Om7035 this is a well documented issue to consider

Not all of it is a valid solution

for example,
NftId is a dataclass which will generate its own repr method hidden by default
@DataClass(frozen=True, init=False)
class NftId:

Read more about it here
https://docs.python.org/3/library/dataclasses.html

TokenTransfer
and
TokenNftTransfer
are not data classes so may benefit from a repr method
Since they have a str but not repr method, I think those would benefit.

@Om7035 how about I save this issue for you, for just one of the classes (either TokenNftTransfer TokenTransfer) or but only assign it to you once you demonstrate you meet the following criteria:

• verified commits
• working from a branch
• one issue per PR
  The reason why just one class is it requires testing and adding to examples, making it a really big PR.

[exploreriii]

@Om7035 I see you have no outstanding pull requests, will you be working on one of these sub-issues?

[Om7035]

Yess @exploreriii

[exploreriii]

@manishdait are you able to check if this issue will conflict with your token transfer? Thank you

[manishdait]

It will not have any conflict.