return unicode_.encode(to_encoding[0], 'replace')

    return safe_str

def remove_suffix(s, suffix):

    if s.endswith(suffix):

        s = s[:-1 * len(suffix)]

    return s

def remove_prefix(s, prefix):

    if s.startswith(prefix):

        s = s[len(prefix):]

    return s

def engine_from_config(configuration, prefix='sqlalchemy.', **kwargs):

    """

    Custom engine_from_config functions that makes sure we use NullPool for

    file based sqlite databases. This prevents errors on sqlite. This only

    applies to sqlalchemy versions < 0.7.0

    """

    import sqlalchemy

    from sqlalchemy import engine_from_config as efc

    import logging

    if int(sqlalchemy.__version__.split('.')[1]) < 7:

        # This solution should work for sqlalchemy < 0.7.0, and should use

        # proxy=TimerProxy() for execution time profiling

        from sqlalchemy.pool import NullPool

        url = configuration[prefix + 'url']

        if url.startswith('sqlite'):

            kwargs.update({'poolclass': NullPool})

        return efc(configuration, prefix, **kwargs)

    else:

        import time

        from sqlalchemy import event

        from sqlalchemy.engine import Engine

        log = logging.getLogger('sqlalchemy.engine')

        BLACK, RED, GREEN, YELLOW, BLUE, MAGENTA, CYAN, WHITE = xrange(30, 38)

        engine = efc(configuration, prefix, **kwargs)

        def color_sql(sql):

            COLOR_SEQ = "\033[1;%dm"

            COLOR_SQL = YELLOW

            normal = '\x1b[0m'

            return ''.join([COLOR_SEQ % COLOR_SQL, sql, normal])

        if configuration['debug']:

            #attach events only for debug configuration

            def before_cursor_execute(conn, cursor, statement,

                                    parameters, context, executemany):

                context._query_start_time = time.time()

                log.info(color_sql(">>>>> STARTING QUERY >>>>>"))

            def after_cursor_execute(conn, cursor, statement,

                                    parameters, context, executemany):

                total = time.time() - context._query_start_time

                log.info(color_sql("<<<<< TOTAL TIME: %f <<<<<" % total))

            event.listen(engine, "before_cursor_execute",

                         before_cursor_execute)

            event.listen(engine, "after_cursor_execute",

                         after_cursor_execute)

    return engine

def age(prevdate):

    """

    turns a datetime into an age string.

    :param prevdate: datetime object

    :rtype: unicode

    :returns: unicode words describing age

    """

    now = datetime.datetime.now()

    now = now.replace(microsecond=0)

    order = ['year', 'month', 'day', 'hour', 'minute', 'second']

    deltas = {}

    future = False

    if prevdate > now:

        now, prevdate = prevdate, now

        future = True

    # Get date parts deltas

    for part in order:

        if future:

            deltas[part] = getattr(d, part + 's')

        else:

            deltas[part] = getattr(now, part) - getattr(prevdate, part)

    # Fix negative offsets (there is 1 second between 10:59:59 and 11:00:00,

    # not 1 hour, -59 minutes and -59 seconds)

    for num, length in [(5, 60), (4, 60), (3, 24)]:  # seconds, minutes, hours

        part = order[num]

        carry_part = order[num - 1]

        if deltas[part] < 0:

            deltas[part] += length

            deltas[carry_part] -= 1

    # Same thing for days except that the increment depends on the (variable)

    # number of days in the month

    month_lengths = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]

    if deltas['day'] < 0:

        if prevdate.month == 2 and (prevdate.year % 4 == 0 and

            (prevdate.year % 100 != 0 or prevdate.year % 400 == 0)):

            deltas['day'] += 29

        else:

            deltas['day'] += month_lengths[prevdate.month - 1]

        deltas['month'] -= 1

    if deltas['month'] < 0:

        deltas['month'] += 12

        deltas['year'] -= 1

    # Format the result

    fmt_funcs = {

        'year': lambda d: ungettext(u'%d year', '%d years', d) % d,

        'month': lambda d: ungettext(u'%d month', '%d months', d) % d,

        'day': lambda d: ungettext(u'%d day', '%d days', d) % d,

        'hour': lambda d: ungettext(u'%d hour', '%d hours', d) % d,

        'minute': lambda d: ungettext(u'%d minute', '%d minutes', d) % d,

        'second': lambda d: ungettext(u'%d second', '%d seconds', d) % d,

    }

    for i, part in enumerate(order):

        value = deltas[part]

        if value == 0:

            continue

        if i < 5:

            sub_part = order[i + 1]

            sub_value = deltas[sub_part]

        else:

            sub_value = 0

        if sub_value == 0:

            if future:

                return _(u'in %s') % fmt_funcs[part](value)

            else:

                return _(u'%s ago') % fmt_funcs[part](value)

        if future:

            return _(u'in %s and %s') % (fmt_funcs[part](value),

                fmt_funcs[sub_part](sub_value))

        else:

            return _(u'%s and %s ago') % (fmt_funcs[part](value),

                fmt_funcs[sub_part](sub_value))

    return _(u'just now')

def uri_filter(uri):

    """

    Removes user:password from given url string

    :param uri:

    :rtype: unicode

    :returns: filtered list of strings

    """

    if not uri:

        return ''

    proto = ''

    for pat in ('https://', 'http://'):

        if uri.startswith(pat):

            uri = uri[len(pat):]

            proto = pat

            break

    # remove passwords and username

    uri = uri[uri.find('@') + 1:]

    # get the port

    cred_pos = uri.find(':')

    if cred_pos == -1:

        host, port = uri, None

    else:

        host, port = uri[:cred_pos], uri[cred_pos + 1:]

    return filter(None, [proto, host, port])