A string output stream is a special object that may be used to buffer arbitrarily long streams
of data. They are useful for handling data that would not otherwise fit within normal varchar size limitations. The
HTTP output functions optionally take a string output stream handle as a parameter and then output to said stream
instead of the HTTP client. A string output stream can be assigned to a database column in insert or update, causing
the characters written to the stream to be assigned to the column as a narrow string. The function string_output_string can
be used to produce a varchar out of a string output stream. It may be called repeatedly to obtain several copies of
the data. http_rewrite can be used to flush a string output stream. If a string output stream is passed to the function
result the data stored in it is sent to the client. The string output object cannot be copied. It cannot therefore be
assigned between two variables or passed by value (as an IN parameter.) It can be passed by reference (OUT, INOUT parameter.)