This method injects an instance
variable unconverted_fields into row and an accessor
method for row called unconverted_fields(). The variable is set
to the contents of fields.
# File lib/csv.rb, line 2264
def add_unconverted_fields(row, fields)
class << row
attr_reader :unconverted_fields
end
row.instance_variable_set(:@unconverted_fields, fields)
row
end