>>> astring = 'Hello'
# 最直接的方法
>>> alist = list(astring)
>>> alist
['H', 'e', 'l', 'l', 'o']
# 列表推导
>>> alist = [ch for ch in astring]
>>> alist
['H', 'e', 'l', 'l', 'o']
# 循环法
>>> alist = []
>>> for ch in astring:
... alist.append(ch)
...
>>> alist
['H', 'e', 'l', 'l', 'o']