How I know where is anything in a list?

# For a list you can use 'index'. It throws error if item not found

>>> my_list = list('Hello')                 
>>> 'H' in my_list  
True
>>> my_list.index('H')
0
>>> my_list.index('l')
2
>>> my_list.index('z')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: 'z' is not in list

# Strings can act like lists
>>> my_string = 'Hello'
>>> 'H' in my_string
True
# find returns index, or '-1' if not found
>>> my_string.find('l')
2
>>> my_string.find('z')
-1

# Can also use 'index()'. It throws error if item not found
>>> my_string.index('o')
4
>>> my_string.index('z')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: substring not found

# can use 'index' on string but throws an error if target not found