add missing function to genderequality

vignettes/genderequality.Rmd

@@ -52,6 +52,12 @@ by reading the gender from the master data of all members of parliament, which i
 fetched from bundestag.de.
 
 ```{r}
+xml_get <- function(node, name) {
+    res <- xml_text(xml_find_all(node, name))
+    if (length(res) == 0) NA_character_
+    else res
+}
+
 x <- read_xml("../inst/masterdata.xml")
 mdbs <- xml_find_all(x, "MDB")