lib/sbdb/db.rb
def each key = nil, val = nil, &exe
			cursor {|c| c.each key, val, &exe }
		end
def each key = nil, val = nil, &exe
			cursor {|c| c.each key, val, &exe }
		end
Arguments:
 * file
 * name
 * type
 * flags
 * mode
 * env
 or: **file**, **opts**. *opts* must be a *::Hash* with keys like above, excluded *file*.