docs: def _handle_sample_line(self, parsed_samples=None):
          """"Check and interpret the "##CHROM" line and return samples"""
          if not self._line or not self._line.startswith("#CHROM"):
              raise exceptions.IncorrectVCFFormat('Missing line starting with "#CHROM"')
          # check for space before INFO
          line = self._line.rstrip()
          pos = line.find("FORMAT") if ("FORMAT" in line) else line.find("INFO")
          if pos == -1:
              raise exceptions.IncorrectVCFFormat('Ill-formatted line starting with "#CHROM"')
          if " " in line[:pos]:
              warnings.warn(
                  (
                      "Found space in #CHROM line, splitting at whitespace "
                      "instead of tab; this VCF file is ill-formatted"
                  ),
                  SpaceInChromLine,
              )
              arr = self._line.rstrip().split()
          else:
              arr = self._line.rstrip().split("\t")
  
          self._check_samples_line(arr)
          return header.SamplesInfos(arr[len(REQUIRE_SAMPLE_HEADER) :], parsed_samples)