def trim_fasta(fasta_lines, output_length):
 for (seq_id, seq) in parse_fasta(fasta_lines):
  (yield ('>%s\n%s\n' % (seq_id, seq[:output_length])))

def trim_fasta ( fasta_lines , output_length ) : for ( seq_id , seq ) in parse_fasta ( fasta_lines ) : ( yield ( '>%s\n%s\n' % ( seq_id , seq [ : output_length ] ) ) )
trim fasta seqs to output_length bases .