How do I trim whitespace from a string?

How do I remove leading and trailing whitespace from a string in Python?

" Hello world " --> "Hello world"
" Hello world"  --> "Hello world"
"Hello world "  --> "Hello world"
"Hello world"   --> "Hello world"

To remove all whitespace surrounding a string, use .strip(). Examples:

>>> ' Hello '.strip()
'Hello'
>>> ' Hello'.strip()
'Hello'
>>> 'Bob has a cat'.strip()
'Bob has a cat'
>>> '   Hello   '.strip()  # ALL consecutive spaces at both ends removed
'Hello'

Note that str.strip() removes all whitespace characters, including tabs and newlines. To remove only spaces, specify the specific character to remove as an argument to strip:

>>> "  Hello\n  ".strip(" ")
'Hello\n'

To remove only one space at most:

def strip_one_space(s):
    if s.endswith(" "): s = s[:-1]
    if s.startswith(" "): s = s[1:]
    return s

>>> strip_one_space("   Hello ")
'  Hello'

Stack Overflow Q#761804, score: 2013