'Get a specific tag key by Name
:param name: Name of the tag key you want (required)
:type  name: ``str``
:rtype: :class:`DimensionDataTagKey`'

def ex_get_tag_key_by_name(self, name):

    tag_keys = self.ex_list_tag_keys(name=name)
    if (len(tag_keys) != 1):
        raise ValueError(('No    tags    found    with    name    %s' % name))
    return tag_keys[0]
