【7-1】
▲簡単な関数
-------------------
>>> def function():
...     print("abc")
...
>>> function()
abc
-------------------


▲関数内での複数の関数呼び出し
-------------------
>>> def function():
...     for i in range(5):
...         print(i)
...
>>> function()
0
1
2
3
4
-------------------


▲関数内で定義した変数は関数内だけで使える
-------------------
>>> print(i)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'i' is not defined
-------------------


▲関数にオブジェクトを渡す
-------------------
>>> def function(x, y):
...     print(x + y)
...
>>> function(10, 1)
11
-------------------


▲関数に変数を渡す
-------------------
>>> a = 'abc'
>>> def function(text):
...     print(text)
...
>>> function(a)
abc
-------------------


▲グローバル変数
-------------------
>>> a = 'abc'
>>> def function():
...    global a
...    print(a)
...    a = 123
...
>>> function()
abc
>>> print(a)
123
-------------------


【7-2】
▲戻り値のない場合
-------------------
>>> def function():
...     print('abc')
...     return
...
>>> a = function()
abc
>>> print(a)
None
-------------------


▲戻り値を指定する場合
-------------------
>>> def function():
...     print('abc')
...     return 'def'
...
>>> a = function()
abc
>>> print(a)
def
-------------------


▲複数の戻り値から選択
-------------------
>>> def function():
...     a = 'abc'
...     if 'z' in a:
...         return 'yes'
...     else:
...         return 'no'
...
>>> a = function()
>>> print(a)
no
-------------------


▲複数の戻り値を渡せる
-------------------
>>> def function():
...     a = 123
...     b = 'abc'
...     return a, b
...
>>> d, e = function()
>>> print(d)
123
>>> print(e)
abc
-------------------


▲リストを戻り値にする
-------------------
>>> def function():
...     a = 123
...     b = 'abc'
...     return [a, b]
...
>>> new_list = function()
>>> print(new_list)
[123, 'abc']
-------------------


▲タプルを戻り値にする
-------------------
>>> def function():
...     a = 123
...     b = 'abc'
...     return (a, b)
...
>>> new_tuple = function()
>>> print(new_tuple)
{123, 'abc'}
-------------------


▲辞書を戻り値にする
-------------------
>>> def function():
...     a = 123
...     b = 'abc'
...     return {1:a, 2:b}
...
>>> new_dict = function()
>>> print(new_dict)
{1: 123, 2: 'abc'}
-------------------