The implementation of urllib.quote, as of Python2.7.

urllib_quote.py

_safe_quoters = {}
always_safe = ('ABCDEFGHIJKLMNOPQRSTUVWXYZ'
               'abcdefghijklmnopqrstuvwxyz'
               '0123456789' '_.-')
_safe_map = {}
for i, c in zip(xrange(256), str(bytearray(xrange(256)))):
    _safe_map[c] = c if (i < 128 and c in always_safe) else '%{:02X}'.format(i)
def quote(s, safe='/'):
    """quote('abc def') -> 'abc%20def'

    Each part of a URL, e.g. the path info, the query, etc., has a
    different set of reserved characters that must be quoted.

    RFC 2396 Uniform Resource Identifiers (URI): Generic Syntax lists
    the following reserved characters.

    reserved    = ";" | "/" | "?" | ":" | "@" | "&" | "=" | "+" |
                  "$" | ","

    Each of these characters is reserved in some component of a URL,
    but not necessarily in all of them.

    By default, the quote function is intended for quoting the path
    section of a URL.  Thus, it will not encode '/'.  This character
    is reserved, but in typical usage the quote function is being
    called on a path where the existing slash characters are used as
    reserved characters.
    """
    # fastpath
    if not s:
        if s is None:
            raise TypeError('None object cannot be quoted')
        return s
    cachekey = (safe, always_safe)
    try:
        (quoter, safe) = _safe_quoters[cachekey]
    except KeyError:
        safe_map = _safe_map.copy()
        safe_map.update([(c, c) for c in safe])
        quoter = safe_map.__getitem__
        safe = always_safe + safe
        _safe_quoters[cachekey] = (quoter, safe)
    if not s.rstrip(safe):
        return s
    return ''.join(map(quoter, s))