code: def _write_vcf_header(out_handle):
      
      def w(line):
          out_handle.write("{0}\n".format(line))
      w('##fileformat=VCFv4.1')
      w('##INFO=<ID=IMPRECISE,Number=0,Type=Flag,Description="Imprecise structural variation">')
      w('##INFO=<ID=END,Number=1,Type=Integer,'
        'Description="End position of the variant described in this record">')
      w('##INFO=<ID=CIPOS,Number=2,Type=Integer,'
        'Description="Confidence interval around POS for imprecise variants">')
      w('##INFO=<ID=CIEND,Number=2,Type=Integer,'
        'Description="Confidence interval around END for imprecise variants">')
      w('##INFO=<ID=SVLEN,Number=.,Type=Integer,'
        'Description="Difference in length between REF and ALT alleles">')
      w('##INFO=<ID=SVTYPE,Number=1,Type=String,Description="Type of structural variant">')
      w('##INFO=<ID=MATEID,Number=.,Type=String,Description="ID of mate breakends">')
      w('##INFO=<ID=EVENT,Number=1,Type=String,Description="ID of event associated to breakend">')
      w('##ALT=<ID=DEL,Description="Deletion">')
      w('##ALT=<ID=INV,Description="Inversion">')
      w('##ALT=<ID=DUP,Description="Duplication">')
      w('##ALT=<ID=DUP:TANDEM,Description="Tandem Duplication">')
      w('##source=hydra')
      w("#" + "\t".join(["CHROM", "POS", "ID", "REF", "ALT", "QUAL", "FILTER", "INFO"]))
docs: Write VCF header information for Hydra structural variant.