dump - print parts of the design in RTLIL format

yosys> help dump
dump [options] [selection]
Write the selected parts of the design to the console or specified file in
RTLIL format.
also dump the module headers, even if only parts of a single
module is selected
only dump the module headers if the entire module is selected
-o <filename>
write to the specified file.
-a <filename>
like -outfile but append instead of overwrite