# File merb-core/lib/merb-core/rack/middleware/content_length.rb, line 7
 7:       def call(env)
 8:         status, headers, body = @app.call(env)
 9: 
10:         # to_s is because Rack spec expects header
11:         # values to be iterable and yield strings
12:         header = 'Content-Length'.freeze
13:         headers[header] = body.size.to_s unless headers.has_key?(header)
14: 
15:         [status, headers, body]
16:       end