def extract(marc_record)
      results = []

      self.each_matching_line(marc_record) do |field, spec|
        if control_field?(field)
          results << (spec.bytes ? field.value.byteslice(spec.bytes) : field.value)
        else
          results.concat collect_subfields(field, spec)
        end
      end

      return results
    end
def extract(marc_record)
      results = []

      self.each_matching_line(marc_record) do |field, spec|
        if control_field?(field)
          results << (spec.bytes ? field.value.byteslice(spec.bytes) : field.value)
        else
          results.concat collect_subfields(field, spec)
        end
      end

      return results
    end
Returns array of strings from a MARC::Record, extracted values. May be empty array.