Hash-like access to tags. Time complexity is O(number of tags).
If tag with such key is not found, returned value 'is nothing'.
If key length is different from 2, exception is thrown.
Special case when value represents nothing is used for removing tag
(assuming that no more than one with this key is presented in the record).
Hash-like access to tags. Time complexity is O(number of tags).
If tag with such key is not found, returned value 'is nothing'.
If key length is different from 2, exception is thrown.
Special case when value represents nothing is used for removing tag (assuming that no more than one with this key is presented in the record).