code: def variant(self, case_id, variant_id):
          
          case_obj = self.case(case_id=case_id)
          vcf_file_path = case_obj.variant_source
          self.head = get_header(vcf_file_path)
  
          self.vep_header = self.head.vep_columns
          self.snpeff_header = self.head.snpeff_columns
  
          handle = VCF(vcf_file_path)
  
          for index, variant in enumerate(handle):
              index += 1
              line_id = get_variant_id(variant_line=str(variant)).lstrip('chrCHR')
              if line_id == variant_id:
                  return self._format_variants(
                      variant=variant,
                      index=index,
                      case_obj=case_obj,
                      add_all_info=True
                      )
  
          return None
docs: Return a specific variant.
  
              Args:
                  case_id (str): Path to vcf file
                  variant_id (str): A variant id
  
              Returns:
                  variant (Variant): The variant object for the given id