R4RS 6.10  (open-output-file filename)  ==>  output-port

Takes a string naming an output file to be created and returns an
output port capable of writing characters to a new file by that
name. If the file cannot be opened, an error is signalled. If a
file with the given name already exists, the effect is unspecified.

S9fES silently overwrites the existing file when the file specified
in STRING already exists.
