HSTRLEN key field
This command seeks the length of a string value that is associated with the given
field in a hash table that is associated with the given
fielddoes not exist, 0 is returned.
keyis associated with a non-hash-table value, an error is raised.
Returns the length of the specified string.
$ HMSET yugahash L1 America L2 Europe
$ HSTRLEN yugahash L1