Change `member` to return nil if not found
Use camel case
Rename UNDEF opcode to VOID
Remove nil local variable
Add `append!` function
Show illegal parameter error message
Check function parameter name not duplicated
Return itself from write/ss
Return nil when `and` failed
Simplify function names for hash table
Use format function in write/ss
Change `write/ss-construct` not to return table
Simplify condition check
Remove unnecessary do
Make write/ss-construct as general function
Add `char-at` and `string-length` functions
Add `nwith` macro (named-with)
Change `map` to accept symbol
Pass command line arguments to main function
Add a tool to show how many times each opcode is appearred