import re


def parse_show_vlan_summary(raw_result):
    """
    Parse the 'show vlan summary' command raw output.

    :param str raw_result: vtysh raw result string.
    :rtype: dict
    :return: The parsed result of the show vlan summary command in a \
        dictionary of the form:

     ::

        {
            'vlan_count': '4'
        }
    """

    show_re = (
        r'Number\s+of\s+existing\s+VLANs:\s+(?P<vlan_count>\d+)'
    )

    re_result = re.search(show_re, raw_result)
    assert re_result

    result = re_result.groupdict()
    return result