chore: What are Type hints?-rest

Signed-off-by: exploreriii <133720349+exploreriii@users.noreply.github.com>

Author: exploreriii

README_types.md

@@ -43,3 +43,163 @@ y: float     = 1.0
 frozen: bool = True
 name: str    = "Rupert"
 
+## What are Type Hints?
+
+Type hints let you declare the expected types of variables, function parameters, and return values.
+
+### When to Use Type Hints
+- **Variables**
+- **Function parameters**
+- **Return values**
+
+> **Note:** Inline type hints are preferred over repeating types in docstrings, which can lead to duplication and maintenance overhead. If you do include types in docstrings, they must match the inline annotations exactly.
+
+---
+
+### Examples
+
+#### Correct
+name: str = ""
+
+def greet(name: str) -> str:
+    """Return a personalized greeting."""
+    return f"Hello, {name}!"
+
+print(greet("Beatrice"))
+
+#### Incorrect
+name: str = ""
+
+def greet(name: str) -> str:
+    """
+    Return a personalized greeting.
+
+    Args:
+        name (int):  ❌ wrong type here!
+
+    Returns:
+        bool:       ❌ wrong type here!
+    """
+    return f"Hello, {name}!"
+
+print(greet("Beatrice"))
+
+## Why Type Hint?
+
+Correct type handling is necessary for the proper functioning of code.
+
+Proper type hinting enables developers to:
+
+- **Understand** the intended data structures and interfaces  
+- **Maintain** and navigate the codebase more easily  
+- **Refactor** with confidence, catching mismatches early  
+- **Extend** the code and documentation without introducing errors  
+
+Additionally, type hints unlock the use of static analysis tools (like MyPy), allowing you to catch type-related bugs before runtime and ship more robust code.
+
+## Typing Using the `typing` Module
+
+Most common types (e.g., `str`, `int`, `float`, `bool`, `bytes`, `list`, `dict`, `tuple`, `set`, `None`) are built-in in Python 3.10+. For more advanced or generic types, import from the `typing` module:
+
+from typing import (
+    Any,            # “escape hatch” for unknown types
+    Union,         # still available, though often replaced by |
+    Optional,      # same as Union[..., None]
+    Callable,      # for callables with specific signatures
+    TypeVar, Generic,  # for custom generics
+    ClassVar,      # annotate class-level constants
+    Literal, Final,  # exact values & constants
+    TypedDict,     # dicts with fixed key types
+    Protocol,      # structural/subtype interfaces
+    NewType,       # distinct alias for an existing type
+    TypeAlias,     # name a complex type
+    Annotated,     # add metadata to existing types
+    ParamSpec, Concatenate,  # for decorator/dependent signatures
+    overload, cast, NoReturn,  # various mypy helpers
+)
+
+### Example
+from typing import TypedDict, Literal
+
+class User(TypedDict):
+    id:     int
+    name:   str
+    active: bool
+
+Status = Literal["pending", "active", "disabled"]
+
+def find_user(uid: int) -> User | None:
+    """
+    Lookup a user by ID.
+    Returns a `User` dict if found, or `None` otherwise.
+    """
+    if uid == 1:
+        return {"id": 1, "name": "Alice", "active": True}
+    return None
+
+## Custom Types
+
+You can use custom types whenever you’ve defined your own classes.
+
+### Example
+from dataclasses import dataclass
+from hiero_sdk import CryptoGetAccountBalanceQuery
+
+@dataclass
+class AccountId:
+    shard:  int
+    realm:  int
+    serial: int
+
+def query_hbar_balance(account: AccountId) -> None:
+    """
+    Fetch and print the Hbar balance for the given AccountId.
+    """
+    balance = CryptoGetAccountBalanceQuery(account)
+    print(f"Your Hbar balance is: {balance.hbars}")
+
+if __name__ == "__main__":
+    account = AccountId(0, 0, 200)
+    query_hbar_balance(account)
+
+## Installing and Using MyPy
+
+Use MyPy to help check for correct typing in your code and its imports. You can adopt type hints gradually—MyPy will not:
+
+- Prevent or change the running of your code  
+- By default, check untyped code  
+
+This makes MyPy safe to introduce at your own pace.
+
+### Install MyPy
+
+```bash
+pip install mypy
+
+Command to check type hinting with MyPy for program.py:
+mypy path/to/program.py
+E.g.
+mypy src/hiero_sdk_python/tokens/token_info.py
+
+Read about MyPy:
+https://mypy.readthedocs.io/en/stable/
+
+Mypy cheatsheet:
+https://mypy.readthedocs.io/en/stable/cheat_sheet_py3.html#cheat-sheet-py3
+
+## Configuring MyPy
+
+By default, MyPy is a very strict type checker. This project includes a `mypy.ini` at `/mypy.ini` to enable gradual, module-by-module checking. You can customize it to suit your needs:
+
+```ini
+# Do not error on imports that lack type stubs
+ignore_missing_imports = True
+
+# Allow parameters to default to None without forcing X | None annotations
+implicit_optional = True
+
+# Suppress errors when calling functions without type annotations
+allow_untyped_calls = True
+
+For a full list of flags and options, see the MyPy command-line reference:
+https://mypy.readthedocs.io/en/stable/command_line.html#command-line