add t addr adds addr to the address greylist.

clear t removes all address greylistings.

gc t removes some address greylistings (the oldest have a higher probability to be removed, yet due to the underlying probabilistic structure, recent greylistings can be dropped).

mem t addr tells if addr is greylisted, but may return a false positive due to the underlying probabilistic structure.

fill_percentage t returns the percentage (in the 0,1 interval) of bloom filter cells which are nonzero.

life_expectancy_histogram t returns the life expectancy distribution of cells (measured in gc calls) stored as an array: the value at index k stores the number of cells that are k calls to gc away from being removed from the greylist.

list t if list_not_reliable_since t returns None, returns the list of currently greylisted IPs. Else it return the list of all ips greylisted since `list_not_reliable_since`