CL-USER> (with-open-file (stream "~/Downloads/israel.osm.pbf" :direction :input :element-type '(unsigned-byte 8))
           (let* ((blob-header-size (nibbles:read-ub32/be stream))
                  (blob-header-buffer (make-array blob-header-size :element-type '(unsigned-byte 8))))
             (read-sequence blob-header-buffer stream)
             (proto:deserialize-object-from-bytes 'osmpbf:blob-header blob-header-buffer)))
#<OSMPBF:BLOB-HEADER {101040C623}>
13
CL-USER> (describe *)
#<OSMPBF:BLOB-HEADER {101040C623}>
  [standard-object]

Slots with :INSTANCE allocation:
  TYPE                           = "OSMHeader"
  INDEXDATA                      = NIL
  DATASIZE                       = 49
; No value