# select all stones
% stone.pl
% stone.pl '*'

# select only stones whose names match a wildcard
% stone.pl 'p*'

# blue stones starting with p
% stone.pl 'p*' -color blue

# blue or green stones
% stone.pl 'p*' -color blue -o -color green

# discard stones tagged as expensive and not tagged as valuable
% stone.pl -tag +expensive -and -tag -valuable -discard