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Add module functools
1 parent 29bbfc2 commit 1bf1645

12 files changed

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‎module_functools/functools_cmp_to_key.py‎

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import functools
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class MyObject:
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def __init__(self, val):
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self.val = val
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def __str__(self):
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return 'MyObject({})'.format(self.val)
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def compare_obj(a, b):
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"""Old-style comparison function."""
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print('comparing {} and {}'.format(a, b))
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if a.val < b.val:
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return -1
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elif a.val > b.val:
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return 1
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return 0
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# Make a key function using cmp_to_key()
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get_key = functools.cmp_to_key(compare_obj)
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def get_key_wrapper(o):
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"""Wrapper function for get_key to allow for print statements."""
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new_key = get_key(o)
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print('key_wrapper({}) -> {!r}'.format(o, new_key))
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return new_key
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objs = [MyObject(x) for x in range(5, 0, -1)]
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for o in sorted(objs, key=get_key_wrapper):
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print(o)
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‎module_functools/functools_lru_cache.py‎

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import functools
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@functools.lru_cache()
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def expensive(a, b):
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print('expensive({}, {})'.format(a, b))
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return a * b
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MAX = 2
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print('First set of calls: ')
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for i in range(MAX):
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for j in range(MAX):
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expensive(i, j)
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print(expensive.cache_info())
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print('\nSecond set of calls')
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for i in range(MAX + 1):
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for j in range(MAX + 1):
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expensive(i, j)
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print(expensive.cache_info())
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print('\nClearing cache: ')
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expensive.cache_clear()
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print(expensive.cache_info())
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print('\nThird set of calls: ')
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for i in range(MAX):
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for j in range(MAX):
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expensive(i, j)
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print(expensive.cache_info())
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‎module_functools/functools_lru_cache_arguments.py‎

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import functools
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@functools.lru_cache(maxsize=2)
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def expensive(a, b):
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print('called expensive({}, {})'.format(a, b))
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return a * b
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def make_call(a, b):
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print('({}, {})'.format(a, b), end=' ')
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pre_hits = expensive.cache_info().hits
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expensive(a, b)
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post_hits = expensive.cache_info().hits
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if post_hits > pre_hits:
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print('cache hit')
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make_call(1, 2)
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try:
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make_call([1], 2)
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except TypeError as err:
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print('ERROR: {}'.format(err))
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try:
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make_call(1, {'2': 'two'})
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except TypeError as err:
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print('ERROR: {}'.format(err))
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‎module_functools/functools_lru_cache_expire.py‎

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import functools
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@functools.lru_cache(maxsize=2)
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def expensive(a, b):
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print('called expensive({}, {})'.format(a, b))
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return a * b
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def make_call(a, b):
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print('({}, {})'.format(a, b), end=' ')
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pre_hits = expensive.cache_info().hits
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expensive(a, b)
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post_hits = expensive.cache_info().hits
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if post_hits > pre_hits:
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print('cache hit')
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print('Establish the cache')
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make_call(1, 2)
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make_call(2, 3)
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print('\nUse cache items')
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make_call(1, 2)
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make_call(2, 3)
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print('\nCompute a new value, triggering cache expiration')
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make_call(3, 4)
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print('\nCache still contains one old item')
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make_call(2, 3)
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print('\nOldest item needs to be recomputed')
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make_call(1, 2)
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‎module_functools/functools_partialmethod.py‎

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import functools
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def standalone(self, a=1, b=2):
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"""Standalone function"""
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print('called standalone with: ', (self, a, b))
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if self is not None:
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print('self.attr = ', self.attr)
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class MyClass:
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"""Demonstration class for functools"""
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def __init__(self):
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self.attr = 'instance attribute'
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method1 = functools.partialmethod(standalone)
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method2 = functools.partial(standalone)
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o = MyClass()
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print('standalone')
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standalone(None)
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print()
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print('method1 as partialmethod')
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o.method1()
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print()
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print('method2 as partial')
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try:
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o.method2()
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except TypeError as err:
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print('ERROR: {}'.format(err))
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‎module_functools/functools_reduce.py‎

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import functools
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def do_reduce(a, b):
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print('do_reduce({}, {})'.format(a, b))
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return a + b
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data = range(1, 5)
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print(data)
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result = functools.reduce(do_reduce, data)
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print('result: {}'.format(result))
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‎module_functools/functools_reduce_initializer.py‎

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import functools
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def do_reduce(a, b):
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print('do_reduce({}, {})'.format(a, b))
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return a + b
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data = range(1, 5)
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print(data)
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result = functools.reduce(do_reduce, data, 99)
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print('result: {}'.format(result))

‎module_functools/functools_reduce_short_sequences.py‎

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import functools
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def do_reduce(a, b):
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print('do_reduce({}, {})'.format(a, b))
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return a + b
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print('Single item in sequence: ', functools.reduce(do_reduce, [1]))
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print('Single item in sequence with initializer: ', functools.reduce(do_reduce, [1], 99))
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print('Empty sequence with initializer: ', functools.reduce(do_reduce, [], 99))
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try:
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print('Empty sequence: ', functools.reduce(do_reduce, []))
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except TypeError as err:
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print('ERROR: {}'.format(err))
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‎module_functools/functools_singledispatch.py‎

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import functools
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@functools.singledispatch
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def myfunc(arg):
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print('default myfunc({!r})'.format(arg))
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@myfunc.register(int)
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def myfunc_int(arg):
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print('myfunc_int({})'.format(arg))
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@myfunc.register(list)
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def myfunc_list(arg):
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print('myfunc_list()')
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for item in arg:
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print(' {}'.format(item))
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myfunc('string argument')
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myfunc(1)
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myfunc(2.3)
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myfunc(['a', 'b', 'c'])

‎module_functools/functools_singledispatch_mro.py‎

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import functools
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class A:
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pass
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class B(A):
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pass
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class C(A):
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pass
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class D(B):
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pass
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class E(C, D):
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pass
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@functools.singledispatch
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def myfunc(arg):
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print('default myfunc({})'.format(arg.__class__.__name__))
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@myfunc.register(A)
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def myfunc_A(arg):
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print('myfunc_A({})'.format(arg.__class__.__name__))
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@myfunc.register(B)
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def myfunc_B(arg):
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print('myfunc_B({})'.format(arg.__class__.__name__))
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@myfunc.register(C)
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def myfunc_C(arg):
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print('myfunc_C({})'.format(arg.__class__.__name__))
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myfunc(A())
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myfunc(B())
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myfunc(C())
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myfunc(D())
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myfunc(E())
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