```ruby
# encoding: utf-8
require "bigdecimal"

module Origin
  module Extensions
    module BigDecimal
      module ClassMethods

        def evolve(object)
          return object unless object
          object.to_s
        end
      end
    end
  end
end

::BigDecimal.__send__(:extend, Origin::Extensions::BigDecimal::ClassMethods)
```

Update big decimal extension doc
user
```ruby
# encoding: utf-8
require "bigdecimal"

module Origin
  module Extensions

    # The big decimal module adds custom behaviour for Origin onto the
    # BigDecimal class.
    module BigDecimal
      module ClassMethods

        # Evolves the big decimal into a MongoDB friendly value - in this case
        # a string.
        #
        # @example Evolve the big decimal
        #   BigDecimal.evolve(decimal)
        #
        # @param [ BigDecimal ] object The object to convert.
        #
        # @return [ String ] The big decimal as a string.
        #
        # @since 1.0.0
        def evolve(object)
          return object unless object
          object.to_s
        end
      end
    end
  end
end

::BigDecimal.__send__(:extend, Origin::Extensions::BigDecimal::ClassMethods)
```
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