def METHOD_NAME(value):
    if value.startswith('@'):
        value = value[1:]
    if value == '':
        # This can only happen if it was '@' initially
        raise ValidationError("Enter twitter name or leave field empty")
    # Twitter have broken our way of checking the username, by always returning 200 OK
    # with an embedded (and not easy to find) error message. We need to re-do this with
    # an authenticated API, but for now we just turn it into a simple regexp validaotor.
    if not re.match('^[a-zA-Z0-9_]+$', value):
        raise ValidationError('Valid Twitter names must contain only the characters a-z, the numbers 0-9, or underscore')
    # Else we skip the check and just say it's fine
    return
    try:
        r = requests.get('https://twitter.com/{0}'.format(value),
                         headers={'User-agent': 'Firefox/60'},
                         timeout=5)
    except requests.exceptions.ReadTimeout:
        raise ValidationError("Could not verify twitter name - timeout")
    if r.status_code != 200:
        raise ValidationError("Could not verify twitter name: {0}".format(r.status_code))
    # All is well! :)