diff --git a/doc/example.R b/doc/example.R
index 0ae7a2a..004e8db 100644
--- a/doc/example.R
+++ b/doc/example.R
@@ -1,6 +1,36 @@
 library(vcfppR)
+library(parallel)
 
 ## Listing 4
+
+par(mfrow = c(3,1), mar = c(5,5,5,2), cex.lab = 2, cex.axis = 2, cex.main = 2)
+
 vcffile <- "https://ftp.1000genomes.ebi.ac.uk/vol1/ftp/data_collections/1000G_2504_high_coverage/working/20201028_3202_raw_GT_with_annot/20201028_CCDG_14151_B01_GRM_WGS_2020-08-05_chr21.recalibrated_variants.vcf.gz"
 vcf <- vcftable(vcffile, region="chr21:1-10000000", samples="NA12878,HG00118,HG00119", format="DP", vartype="snps", pass = TRUE, info = FALSE)
-boxplot(vcf$dp, names=vcf$samples, ylab="Read Depth (DP)")
+
+boxplot(vcf$DP, names=vcf$samples, ylab="Read Depth (DP)")
+
+svfile <-  "https://ftp.1000genomes.ebi.ac.uk/vol1/ftp/data_collections/1000G_2504_high_coverage/working/20210124.SV_Illumina_Integration/1KGP_3202.gatksv_svtools_novelins.freeze_V3.wAF.vcf.gz"
+sv <- vcfsummary(svfile, svtype = TRUE)
+
+boxplot(sv[c("DEL","DUP", "CNV", "INS","INV","CPX","CTX")],
+        main = "SVs per genome stratified by SV types")
+
+vcffiles <- paste0("https://ftp.1000genomes.ebi.ac.uk/vol1/ftp/data_collections/1000G_2504_high_coverage/working/20201028_3202_raw_GT_with_annot/20201028_CCDG_14151_B01_GRM_WGS_2020-08-05_chr", 1:22, ".recalibrated_variants.vcf.gz")
+
+all <- mclapply(vcffiles,
+vcfsummary, pass = TRUE, mc.cores=22)
+
+ped <- read.table("https://ftp.1000genomes.ebi.ac.uk/vol1/ftp/data_collections/1000G_2504_high_coverage/20130606_g1k_3202_samples_ped_population.txt", h=T)
+ped <- ped[order(ped$Superpopulation),]
+supers <- unique(ped$Superpopulation)
+samples <- all[[1]]$samples
+snps <- Reduce("+", lapply(all, "[[", "SNP"))
+indels <- Reduce("+", lapply(all, "[[", "INDEL"))
+o <- sapply(supers, function(pop) {
+  id <- subset(ped, Superpopulation == pop)[,"SampleID"]
+  ord <- match(id, samples)
+  (snps[ord] + indels[ord]) / 1e6
+})
+
+boxplot(o, main = "SNP & INDEL with FILTER=PASS", ylab = "Number of variants per genome (in millions)")
diff --git a/test/bcf-writer.cpp b/test/bcf-writer.cpp
index 7a4277f..58d9e4a 100644
--- a/test/bcf-writer.cpp
+++ b/test/bcf-writer.cpp
@@ -50,3 +50,14 @@ TEST_CASE("Write VCF by copying header from another VCF", "[bcf-writer]")
     br.getNextVariant(v);
     bw.writeRecord(v);
 }
+
+TEST_CASE("init header twice", "[bcf-writer]")
+{
+    BcfReader br("test-vcf-read.vcf");
+    BcfRecord v(br.header);
+    BcfWriter bw("test.vcf", "VCF4.3");
+    bw.initalHeader(br.header);
+    bw.writeHeader();
+    br.getNextVariant(v);
+    bw.writeRecord(v);
+}