def url_fix(s, charset='utf-8'):
    r"""Sometimes you get an URL by a user that just isn't a real URL because
    it contains unsafe characters like ' ' and so on. This function can fix
    some of the problems in a similar way browsers handle data entered by the
    user:

    >>> url_fix(u'http://de.wikipedia.org/wiki/Elf (Begriffskl\xe4rung)')
    'http://de.wikipedia.org/wiki/Elf%20(Begriffskl%C3%A4rung)'

    :param s: the string with the URL to fix.
    :param charset: The target charset for the URL if the url was given as
                    unicode string.
    """
    # First step is to switch to unicode processing and to convert
    # backslashes (which are invalid in URLs anyways) to slashes.  This is
    # consistent with what Chrome does.
    s = to_unicode(s, charset, 'replace').replace('\\', '/')

    # For the specific case that we look like a malformed windows URL
    # we want to fix this up manually:
    if s.startswith('file://') and s[7:8].isalpha() and s[8:10] in (':/', '|/'):
        s = 'file:///' + s[7:]

    url = url_parse(s)
    path = url_quote(url.path, charset, safe='/%+$!*\'(),')
    qs = url_quote_plus(url.query, charset, safe=':&%=+$!*\'(),')
    anchor = url_quote_plus(url.fragment, charset, safe=':&%=+$!*\'(),')
    return to_native(url_unparse((url.scheme, url.encode_netloc(),
                                  path, qs, anchor)))