def default_value(tag)
      name, vr = LIBRARY.name_and_vr(tag)
      conversion = VALUE_CONVERSION[vr]
      case conversion
      when :to_i then return 0
      when :to_f then return 0.0
      else
        # Assume type is string and return an empty string:
        return ''
      end
    end
def default_value(tag)
      name, vr = LIBRARY.name_and_vr(tag)
      conversion = VALUE_CONVERSION[vr]
      case conversion
      when :to_i then return 0
      when :to_f then return 0.0
      else
        # Assume type is string and return an empty string:
        return ''
      end
    end
Determines a default value to use for anonymizing the given tag.

 @param [String] tag a data element tag
 @return [String, Integer, Float] the default replacement value for a given tag