docs: function(lambda) {
           return {
              d: function(x, logp) { return dpois(lambda, logp)(x); },
              p: function(q, lowerTail, logp) {
                 return ppois(lambda, lowerTail, logp)(q);
              },
              q: function(p, lowerTail, logp) {
                 return qpois(lambda, lowerTail, logp)(p);
              },
              r: function() { return rpois(lambda)(); }
           };
        }