pubmed_cv <- function(fl_nm) {
  library(tidyverse)

  readLines("pubmed_result.txt") %>%
  (function(z) z[z != ""]) %>%
  (function(cv) {
    grep("^[0-9]+?:", trimws(cv)) %>%
    list(
      beginnings = .,
      ends = compose(as.numeric, na.omit)(c(lead(.) - 1, length(cv)))
    ) %>%
    pmap_chr(~ reduce(cv[.x:.y], paste, .init = ""))
  }) %>%
  trimws()
}