def method_missing(m, *args, &block)  
      name = m.to_s
      if name =~ /\?$/
        # Query for empty sample name
        @sample_index ||= @header.sample_index
        return !VcfSample::empty?(@fields[@sample_index[name.chop]])
      else
        sample[name]
      end
    end
def method_missing(m, *args, &block)  
      name = m.to_s
      if name =~ /\?$/
        # Query for empty sample name
        @sample_index ||= @header.sample_index
        return !VcfSample::empty?(@fields[@sample_index[name.chop]])
      else
        sample[name]
      end
    end
Return the sample