Build error about LockingTextWriter

[bioinfornatics]

Dear,
i do not understand what is wrong in my code and produce this:

-------------------------
$ ldc2 ../../lib/libdscience-ldc.a -I=../.. fasta.d
/usr/include/d/std/range.d(295): Error: static assert  "Cannot put a
Sequence into a LockingTextWriter"
    instantiatied in /usr/include/d/std/format.d(1512):
put!(LockingTextWriter,Sequence)
    instantiatied in /usr/include/d/std/format.d(1869):
formatRange!(LockingTextWriter,Sequence,char)
    instantiatied in /usr/include/d/std/format.d(2232):
formatValue!(LockingTextWriter,Sequence,char)
    ... (1 instantiations, -v to show) ...
    instantiatied in /usr/include/d/std/stdio.d(684):
formattedWrite!(LockingTextWriter,char,Sequence)
    instantiatied in /usr/include/d/std/stdio.d(1563):
write!(Sequence,char)
    instantiatied in fasta.d(12): writeln!(Sequence)
-------------------------


sequence file can be show here:
https://gitorious.org/dscience/dscience/blobs/master/dscience/molecules/sequence.d


thanks