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### Ports

- `(current-input-port [input-port])` gets or sets an input port used by `read`, `read-char`, `char-ready?`, `read-line`, `read-string`, and `read-string-avail!` when a specific input port is not provided.
- `(current-output-port [output-port])` gets or sets an output port used by `display`, `write`, `print`, `write-char`, and `printf` when a specific output port is not provided.
- `(current-error-port [output-port])` gets or sets an output port used by the default error display handler.
- `(global-port-print-handler [proc])` gets or sets a procedure that takes an arbitrary value and an output port. This global port print handler is called by the default port print handler (see section 11.1.9) to `print` values into a port.