code: def get_colmap(fns, pattern, single_col=False, antipattern=False):
      
      colmap = {}
      for fn in fns:
          header = tsvreader.get_tsv_header(fn)
          basefn = os.path.basename(fn)
          cols = tsvreader.get_cols_in_file(pattern, header, single_col)
          if antipattern:
              anticols = tsvreader.get_cols_in_file(antipattern, header,
                                                    single_col)
              cols = [col for col in cols if col not in anticols]
          if cols:
              colmap[basefn] = cols
      return colmap
docs: For table files, loops through headers and checks which column(s)
      match a passed pattern. Those column(s) names are returned in a map with
      filenames as keys