def field_symbolizer(arg = nil)
      return @field_symbolizer unless arg
      @field_symbolizer = if arg.is_a? Symbol
                            Remi::FieldSymbolizers[arg]
                          else
                            arg
                          end
    end
def field_symbolizer(arg = nil)
      return @field_symbolizer unless arg
      @field_symbolizer = if arg.is_a? Symbol
                            Remi::FieldSymbolizers[arg]
                          else
                            arg
                          end
    end
Field symbolizer used to convert field names into symbols.  This method sets
 the symbolizer for the data subject and also sets the symbolizers for
 any associated parser and encoders.

 @return [Proc] the method for symbolizing field names