unsigned random_port();
string random_port_string(const string &);
+char random_binary();
+string random_binary_string(size_t len);
char random_ascii(char min = '!', char max = '~');
string random_ascii_string(size_t len, char min = '!', char max = '~');
kv_pair random_ascii_pair(size_t minlen = 1<<2, size_t maxlen = 1<<10);