Iterator and Dictionary Utilities

def iterkeys(d: dict, **kw) -> Iterator[Any]
    """Return iterator over dictionary keys."""

def itervalues(d: dict, **kw) -> Iterator[Any]  
    """Return iterator over dictionary values."""

def iteritems(d: dict, **kw) -> Iterator[tuple[Any, Any]]
    """Return iterator over dictionary items as (key, value) pairs."""

def iterlists(d: dict, **kw) -> Iterator[list[Any]]
    """Return iterator over dictionary lists (for MultiDict-like objects)."""

import six

data = {"a": 1, "b": 2, "c": 3}

# Iterate over keys
for key in six.iterkeys(data):
    print(key)  # Prints: a, b, c

# Iterate over values  
for value in six.itervalues(data):
    print(value)  # Prints: 1, 2, 3

# Iterate over items
for key, value in six.iteritems(data):
    print(f"{key}: {value}")  # Prints: a: 1, b: 2, c: 3

# Memory efficient iteration over large dictionaries
large_dict = {str(i): i for i in range(10000)}
for key, value in six.iteritems(large_dict):
    if value > 5000:
        break

def viewkeys(d: dict) -> Any
    """Return dictionary keys view."""

def viewvalues(d: dict) -> Any
    """Return dictionary values view."""  

def viewitems(d: dict) -> Any
    """Return dictionary items view."""

import six

data = {"a": 1, "b": 2, "c": 3}

# Get keys view/equivalent
keys_view = six.viewkeys(data)
print("a" in keys_view)  # True

# Get values view/equivalent  
values_view = six.viewvalues(data)
print(1 in values_view)  # True

# Get items view/equivalent
items_view = six.viewitems(data)
print(("a", 1) in items_view)  # True

# Set operations on views (Python 3 behavior)
dict1 = {"a": 1, "b": 2}
dict2 = {"b": 2, "c": 3}
common_keys = six.viewkeys(dict1) & six.viewkeys(dict2)  # {'b'}

def advance_iterator(it: Iterator) -> Any
    """Advance an iterator by one step and return the next value."""

def next(it: Iterator, default: Any = None) -> Any
    """Get next item from iterator with optional default."""

def callable(obj: Any) -> bool
    """Test if an object is callable."""

import six

# Advance iterator manually
data = iter([1, 2, 3, 4, 5])
first = six.advance_iterator(data)  # 1
second = six.next(data)             # 2

# Use with default value
empty_iter = iter([])
value = six.next(empty_iter, "default")  # "default"

# Test callability
def my_function():
    pass

print(six.callable(my_function))    # True
print(six.callable("string"))      # False
print(six.callable(lambda x: x))   # True

class Iterator:
    """Base iterator class for Python 2 compatibility."""
    def __iter__(self) -> Iterator
    def __next__(self) -> Any

import six

class CountdownIterator(six.Iterator):
    def __init__(self, start):
        self.start = start
    
    def __iter__(self):
        return self
    
    def __next__(self):
        if self.start <= 0:
            raise StopIteration
        self.start -= 1
        return self.start + 1

# Use the iterator
countdown = CountdownIterator(3)
for num in countdown:
    print(num)  # Prints: 3, 2, 1

def get_method_function(method: Any) -> Any
    """Get function from method object."""

def get_method_self(method: Any) -> Any  
    """Get self from method object."""

def get_function_closure(func: Any) -> Any
    """Get closure from function object."""

def get_function_code(func: Any) -> Any
    """Get code object from function."""

def get_function_defaults(func: Any) -> Any
    """Get defaults from function object."""

def get_function_globals(func: Any) -> Any
    """Get globals from function object."""

import six

class MyClass:
    def my_method(self, x, y=10):
        z = x + y
        return lambda: z

obj = MyClass()
method = obj.my_method

# Access method components
func = six.get_method_function(method)      # Unbound function
self_obj = six.get_method_self(method)      # The instance (obj)

# Access function components  
code = six.get_function_code(func)          # Code object
defaults = six.get_function_defaults(func)  # (10,)
globals_dict = six.get_function_globals(func)  # Global namespace

# Example with closure
closure_func = obj.my_method(5)
closure = six.get_function_closure(closure_func)  # Closure variables

def get_unbound_function(func: Any) -> Any
    """Get function from possibly unbound function."""

def create_bound_method(func: Callable, instance: Any) -> Any
    """Create a bound method from function and instance."""

def create_unbound_method(func: Callable, cls: type) -> Any  
    """Create an unbound method from function and class."""

import six

class MyClass:
    def my_method(self):
        return "Hello from method"

# Get unbound function
unbound = six.get_unbound_function(MyClass.my_method)

# Create bound method manually
instance = MyClass()
bound_method = six.create_bound_method(unbound, instance)
result = bound_method()  # "Hello from method"

# Create unbound method (primarily for Python 2 compatibility)
unbound_method = six.create_unbound_method(unbound, MyClass)

import six

# Efficient dictionary processing
def process_large_dict(data_dict):
    """Process dictionary without creating intermediate lists."""
    result = {}
    
    # Memory-efficient iteration
    for key, value in six.iteritems(data_dict):
        if isinstance(value, six.string_types):
            result[key] = value.upper()
        elif six.callable(value):
            result[key] = value()
        else:
            result[key] = str(value)
    
    return result

# Custom iterator with cross-version compatibility
class ChunkedIterator(six.Iterator):
    """Iterator that yields chunks of data."""
    
    def __init__(self, data, chunk_size):
        self.data = iter(data)
        self.chunk_size = chunk_size
    
    def __iter__(self):
        return self
    
    def __next__(self):
        chunk = []
        try:
            for _ in range(self.chunk_size):
                chunk.append(six.next(self.data))
        except StopIteration:
            if chunk:
                return chunk
            raise
        return chunk

# Use chunked iterator
data = range(10)
chunked = ChunkedIterator(data, 3)
for chunk in chunked:
    print(chunk)  # [0, 1, 2], [3, 4, 5], [6, 7, 8], [9]

# Method introspection and modification
def analyze_methods(cls):
    """Analyze all methods in a class."""
    methods_info = {}
    
    for name in dir(cls):
        attr = getattr(cls, name)
        if six.callable(attr) and hasattr(attr, '__func__'):
            func = six.get_method_function(attr) if hasattr(attr, '__self__') else attr
            methods_info[name] = {
                'defaults': six.get_function_defaults(func),
                'code': six.get_function_code(func),
                'arg_count': six.get_function_code(func).co_argcount
            }
    
    return methods_info