With no explanation, label each line with "O", "art-broadcastprogram", "art-film", "art-music", "art-other", "art-painting", "art-writtenart", "building-airport", "building-hospital" or "building-hotel" preceded by ":".
The
nature
of
how
the
mutation
causes
each
of
the
condition
's
symptoms
is
not
well
known
;
however
,
research
is
ongoing
.
The:O
nature:O
of:O
how:O
the:O
mutation:O
causes:O
each:O
of:O
the:O
condition:O
's:O
symptoms:O
is:O
not:O
well:O
known:O
;:O
however:O
,:O
research:O
is:O
ongoing:O
.:O